One of the many evidences for God is the moral sense within each of us. Skeptic Bertrand Russell admitted to man's ethical nature this way: "We feel that the man who brings widespread happiness at the expense of misery to himself is a better man than the man who brings unhappiness to others and happiness to himself. I do not know of any rational ground for this view."
   Philosopher Immanuel Kant also observed that all people have a concern for ethics. In fact, no one can live without a moral sense. He reasoned that these concerns go much deeper than societal standards or parental discipline.
   Further, Kant reasoned that this moral duty is meaningless apart from ultimate justice. He concluded that this universal moral sense demands a moral giver, i.e., God. And this God must be completely just and completely omniscient. One must ask, "Why be ethical if real justice does not prevail?" If ethics is real, there must be judgment for it to have any serious meaning. If death is ultimate, then no ethical mandate is really significant. Since we know that complete justice is not found in this life, if ethics are real and practical, justice demands life beyond death where we will meet the just judge.
   There are logically only two options: either we have full-bodied theism with life after death where true and ultimate justice is meted out, or we have no meaningful basis for our ethical decisions and actions. If there is no God, all of your ethical conclusions are meaningless. While Kant stopped short of embracing God, embracing instead the importance of reason in ethics, he admitted that "We must live as though there were a God."
   In other words, if there is no just God, and morality is flexible, why be moral at all? Carried to its logical conclusion, immoral behavior, even at its worst, does not matter. As explained by R. C. Sproul, a moral choice without God would be an effect without a cause, which is irrational! The agnostic must ask himself, "Why should I be moral today?"
   Put more simply, either God is or God is not. Even atheist Madalyn Murray O'Hair recognized that there is no in between on this issue. She said that an agnostic is just an atheist without guts. As put by Phillip Johnson (in his book Reason in the Balance), it may be rational to argue about whether God is real or unreal, but it is clearly irrational to assume that a God who is real can safely be ignored.
   If God exists, agnosticism is eternally unwise. Blaise Pascal offered his famous "Pascal's Wager." He pointed out that either God is or he is not. To bet that God does not exist, or that you do not know that he exists, has nothing to gain and everything to lose. If God does exist, your only opportunity to win eternal happiness is to believe. If God exists, justice demands total faith, hope, love, obedience, and worship. Because temporal death is certain, one CANNOT NOT CHOOSE to make a decision about God. We must make the wager. Here's a link for more on Pascal's Wager: http://www.peterkreeft.com/topics/pascals-wager.htm.
   Summarizing Scripture, Boa and Moody explain that agnosticism is not simply an intellectual process of reserving judgment. It is really a suppression of the truth that God has implanted within the human heart (Romans 1:18-20).
   R.C. Sproul flatly states that there is nothing more pitiful than the position of the relativist/secular humanist. There is a gaping logical difficulty with the view of those who claim that we came from nowhere and are going to nowhere, yet life is filled with meaning in between! This position is impossibly inconsistent and incoherent.
   From the perspective of evidential history, which philosophy produces meaning and purpose to life: nihilism (the doctrine of ultimate unknowingness) or Christian hope? It was Nietzsche's atheism and Darwin's naturalism that provided the justification for the holocaust. Such is the logical result, taken to the extreme, of life without God. Powerful resources on this subject include those by Zacharias listed in the resource list.