Some God-doubters reject what the Bible says about God, Jesus Christ, and salvation, asserting, "The Bible is full of appealdenied," or "The Resurrection is a myth like other ancient mythology," and so forth. Documented refutations are found in books such as Lee Strobel's The Case for Christ (Zondervan, 1998) and Hank Hanegraaff's Resurrection (Word, 2000).
Still others assert objectivity, absolute truth, and moral certainty without any transcendental Being, or God who is personal, moral, and the creator of all things, both material (the universe and everything in it) and immaterial (minds, concepts, etc.). Objectivist humanist problems against the existence of God include: (1) language and knowledge, (2) ethics and morals, (3) science and scientific methodology, and (4) logic and reasoning. Each can be refuted from a Christian theistic worldview, as in Norman Geisler and Winfried Corduan's Philosophy of Religion (Baker, 1988).
The objectivist humanist accepts assumptions without justification. The principles he or she agrees with (including the reasoning processes he or she uses) are universal, invariant, and abstract, qualitatively different than anything that could be accounted for by matter, energy, and motion over time. These transcendental principles reflect purposefulness and mindfulness, and are meaningless without a transcendental Being whose inherent, eternal nature establishes the foundation upon which the house of reason is built. They are the preconditions of any intelligibility.
Atheism is inadequate to explain the very reasoning processes we use to discuss the existence of God. Intelligibility can not be accounted for apart from God.
"Humanism is an ethical, scientific, and philosophical outlook that has changed the world....[expressing] a renewed confidence in the power of human beings to solve their own problems and conquer uncharted frontiers." This bold Star Trekesque statement of religion, truth, and value without God is proposed by the Humanist Manifesto 2000 (HM2K) as the only adequate worldview. Humanism, as used in HM2K and elsewhere, dismisses belief in God as irrational and irrelevant. Those who reject belief in God call themselves by various names (atheist, agnostic, God-doubter, skeptic, secular humanist, etc.), but the term humanist is an umbrella term including most such people.
The second category of humanists holds a worldview of objectivity, absolute truth, and moral absolutism. Their most visible organ is the Free Inquiry magazine, which published HM2K and whose editor-in-chief is the HM2K's author, Dr. Paul Kurtz. The first part of this article quoted extensively from an issue of Free Inquiry devoted to refuting postmodern humanism. 
Prospects for a Better Future rejects the sinfulness of humanity, the need for salvation, and God's direction of human history according to a benevolent plan of redemption. HM2K places its faith in human reason and science, focusing on numerous historical and scientific advances in human civilization and on numerous lingering or newly emerging problems, especially those attributed to the continuing presence and influence of religion.
The solution to human problems is found in human endeavor coupled with scientific naturalism, producing the benefits of technology in a context of reason and human-based ethics. This will be accomplished by human effort without regard for the existence of God.
In dialogue with Christians, modernist (as opposed to postmodernist) humanists agree on certain assumptions or presuppositions: reality exists; at least one mind exists; truth is absolute and can be known; logic and reasoning (rational inquiry) are tools to help discover truth; communication is possible; and there are valid ways to test conclusions.
While the humanist assumes these factors as "the inherent properties of matter," or "an evolutionary survival mechanism," and so forth, the Christian knows the assumptions are based on the eternal, infinite, unchanging, rational, and moral nature, character, and power of God. Because the human mind and the material world bear the creative, rational imprint of God, we are capable of meaningful contemplation of reality and can know that reality reflects the rational, orderly, predictable design of God.
The argument from language and knowledge, as commonly stated, says "God-talk is meaningless." It is believed that we can never know about God to talk about Him meaningfully, or our experience with God is beyond our mental and linguistic ability to understand or express.
This argument is self-refuting or self-contradictory because the humanist's very assertion is talk about God. God has created humans with the capacity for meaningful language that can describe nonmaterial realities (e.g., concepts, numbers, and God). There is evidence of God's power and nature through the design and order of the material world. Most importantly, God became incarnate in the person of Jesus Christ (John 1:1-18).
Humanists often pose an indictment of God's own moral character called the Problem of Evil. It is usually stated as follows:
Christian theists have responded for centuries with convincing evidence and argumentation. First, if the existence of evil in the world proves that God does not exist, then how does the humanist account for the good in the world? Does the good in the world prove that God does exist? This "Problem of Good" is an unanswerable objection alerting us that the argument is not reasonable.
The humanist has omitted important factors accounting for evil in the world, including (1) the nature of free moral agents; (2) the consequences of their actions; (3) the manner and time in which God judges evil and rewards innocent suffering. God did not create evil, evil beings, or beings who could perform only evil acts. He created morally responsible agents who violated His ethical standard and performed evil, with evil consequences. That the evil is not instantly rectified speaks more to God's patient grace than to any supposed impotence.
When human moral agency and ultimate judgment and reconciliation over time are considered, the "Problem of Evil" evaporates. Norman Geisler reframes it:
Some humanists attack objectivist ethics grounded in God by divorcing the ethical standard from God altogether. This sort of argument is presented by atheist Michael Martin, professor of philosophy at Boston University. Martin tries to deflect the Christian critique of atheist ethics in "Atheism, Christian Theism, and Rape." He summarizes his understanding of two Christian objections to atheistic ethics: (1) Christians accuse atheistic ethics of being relative (dependent on something or someone in particular, like an individual's preferences or a society's heritage) and thus not binding; or (2) being objective (independent of something or someone in particular, like "It's always wrong to torture innocent children") and thus admitting of some absolute, eternal, invariant, universal and abstract standard beyond the mere material universe (a standard Christians say can only came from God's moral character).
Martin then uses the same kinds of arguments to critique Christian theism. He argues against the idea that theistic morality is always presupposed:
Second, Martin argues that if ethics are
Let us assume for the moment that the Biblical position on rape is clear: God condemns rape. But why? One possibility is that He condemns rape because it is wrong. Why is it wrong? It might be supposed that God has various reasons for thinking rape is wrong....However, if these reasons provide objective grounds for God thinking that rape is wrong, then they provide objective grounds for others as well. Moreover, these reasons would hold even if God did not exist. Thus, on this assumption...atheists could provide objective ground for condemning rape - the same grounds used by God.
Let us suppose now that rape is wrong because God condemns it. In this case, God has no reasons for His condemnations. His condemnation makes rape wrong and it would not be wrong if God did not condemn it. Indeed, not raping someone would be wrong if God condemned not raping. However, this hardly provides objective grounds for condemning rape. Whether rape is right or wrong would be based on God's arbitrary condemnation. On this interpretation, if atheists can provide no objective grounds for condemning rape, they are no worse off than theists.
Martin cites these two options as the only valid ones regarding God and ethics. Although he acknowledges that theists argue a third position - "by basing morality on the necessary attributes of God's character"--he wrongly concludes that even that argument distills to God's character being moral because it conforms to an outside standard (to which the atheist can appeal as well) or because it is God's will, which Martin consigns to the arbitrary category.
Martin's argument is a false choice. He limits our choices to two (apart from God or arbitrary) and then asks us to pick one of the two choices. Christian theists do not agree that ethics fit either of those two categories.
The first category, that ethics are apart from God and justified by reason or effect, is an argument for teleological ("ends justifying the means") ethics. Martin may argue that rape is wrong because "it violates the victim's rights, it traumatizes the victim, it undermines the fabric of society," but he has merely pushed the source of an absolute standard back one level - who says violating a victim's rights is wrong? Why is it wrong to traumatize victims? Why does it matter if the fabric of society is undermined?
Martin's saying that ethics from God are merely arbitrary does not deal with the Judeo-Christian argument that the standard is a reflection of God's moral character, not His mere will. Christian theism understands that God's moral character is essential to His very nature and is not willed by Him. In Christian theism, it's the other way around from what Martin suggests. God's will is bound by His nature _ He cannot will to sin; He cannot will to cease existing; He cannot will to suspend the laws of logic; and so on. He is the source for absolute ethics by nature, not by will.
Scientific naturalism enables human beings to construct a coherent worldview disentangled from metaphysics or theology and based on the sciences.
First, scientific naturalism is committed to a set of methodological prescriptions. For methodological naturalism, all hypotheses and theories must be tested experimentally by reference to natural causes and events....
Scientific naturalists hold a form of nonreductive materialism; natural processes and events are best accounted for by reference to material causes. (emphasis in original)
Second, humanists have ignored the empirical evidence from which we can logically infer God's existence. These include the design evident in the universe and the historical evidence for the incarnation, death, and resurrection of "God manifest in the flesh" (John 1:1-14).
This is not the forum for a lengthy scientific analysis of humanism's inadequate naturalism. Others have addressed this issue at length, conclusively making the case that humanism cannot reject the existence of God based on scientific assumptions or evidence.
This category is foundational to the rest. Every nontheistic argument is based on certain assumptions, or presuppositions, without which any argumentation, scientific inquiry, moral judgment, or even language would be impossible.
The acceptance of these assumptions is an admission that there are universal, invariant, and abstract principles qualitatively different than anything that can be accounted for merely by matter, energy, and motion over time; in other words, by the material universe, which is the only reality admitted by the humanist. These transcendental principles reflect purposefulness and are therefore meaningless without a transcendental Being whose inherent, eternal mindfulness establishes the foundation upon which the house of reason is based. They are the preconditions of any actual intelligibility.
Humanists disallow any consideration of reality apart from material existence. They are convinced the only kinds of proofs or tests for discovering or understanding reality are empirical, or sense-oriented. They fail to recognize the obvious: the best empirical test in the world only has significance when it is applied to the material world and the resulting observations are interpreted by logical analysis.
For example, to determine how many chairs are in a room, one can use his eyes (a sense) to count (a logical, mathematical process) the chairs (material things). Testing a statement about something intangible or immaterial doesn't combine the empirical with the rational. In such cases sense-oriented tests are actually inappropriate. To answer a historical question, such as whether Abraham Lincoln was the sixteenth president, one cannot depend on sensory experiments but must use historical investigation. To determine the relationship among the ratios 1:2, 2:4, and 4:8 is not decided by counting sticks, but by logical deduction.
Someone convinced that empirical or "scientific" tests are always adequate possesses a belief that is actually self-contradictory, or self-refuting. Once this is established, the Christian can present a powerful argument for the existence of God called, appropriately, the transcendental argument.
Any humanist who has faith in science also has faith in the laws of logic, the scientific principle that the future will be like the past, and in other "natural laws." He fails, however, to account either for the principles (laws) themselves, or for his ability to reason objectively (make sense) from his observations.
Whether Christian or humanist, we can only make sense of our observations and recognize principles by using the laws of logic. These laws are abstract (nonmaterial), invariant (will not change), universal (not based upon a particular, but applicable to all things), and eternal (independent of the finite universe). The laws of logic cannot come about by material, finite means because they are categorically different.
You can't pour a law of logic into a glass. You can't see a law of logic evolving in matter. (You can, however, use the laws of logic along with observation to determine how much water a glass will hold.)
What is more reasonable to believe, that the nonrational produces the rational; or that a rational being (God) created other rational beings (humans) and a world founded on rational principles that can therefore be understood by these rational beings? The humanist must borrow from the theistic, Christian wordview, which can account for rationality. It is ironic that humanists often accuse Christians of possessing blind faith, when Christians have justification for the scientific method, while the humanist only has blind faith that the nonrational can produce the rational. Christianity gives birth to science, while humanism only gives birth to blindness.
There are many demonstrations of the existence of God in addition to the transcendental argument. Some argue from design. God's nature is reflected in his creation, much as a book reflects the ideas of an author, and yet no one would believe that the book was produced by blind, mindless chance over time.
Despite the rejection of the existence of God based on what at first appear to be sophisticated philosophical and scientific arguments, atheism is a worldview that cannot account for the very universe in which we live, much less the immaterial aspects of reality such as minds, logic, ethics _ even numbers, concepts, and thoughts. The best efforts of contemporary God-doubters, exemplified by HM2K, will not be able to resolve these inherent appealdenied in their worldview. They can only point to how many prestigious philosophers, scientists, and world leaders agree with them that the naked Emperor is indeed resplendently clothed.
The apostle Paul argued to the Greek God-doubters of his day, "God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands. Nor is He worshiped with men's hands, as though He needed anything, since He gives to all life, breath, and all things_in the hope that they might grope for Him and find Him, though He is not far from each one of us; for in Him we live and move and have our being." (Acts 17:24-28a NKJV)