Faith is as impossible to define in fullness as love, but it includes the idea that you owe a personal loyalty to truth, virtue and beauty, and that the mysterious source of truth, virtue and beauty will reward that loyalty and faithfully reciprocate.
Faith is the opposite of nihilism, which is the idea that there are no metaphysical truths, no supernatural reality, no innate purpose to life.
The point of faith is often misunderstood, and, frankly, often lied about. Matters of faith are neither illogical nor do they lack evidence.
The confusion comes because no other decision in life (even such all-embracing decisions as the decision to marry or to join the army) requires loyalty from every part of your soul and every nook of your psychology; including the part that decides.
All other decisions but this one allow you a place to stand, a neutral ground, a judge’s bench, where you can weigh the arguments for and against and make the decision according to rules that are themselves not part of the decision. But in this case, whether you become a Christian or become a Political Correction Cultist, there is no neutral ground.
You cannot make the decision based on the truth of the claims, because Political Correctness rejects the concept of truth whereas Christianity says Christ is truth.
You cannot make the decision based on the virtue of the claims, because Political Correctness rejects the concept of virtue, and says that all moral good or evil is a human invention, or the imposition of mindless genetic processes.
You cannot make a decision based on the beauty of the claims, because Political Correctness rejects the concept of beauty as trivial and trite, and rejects the concept that beauty reflects truth.
You cannot make the decision based on the rationality of the claim, because Political Correctness rejects the idea of objective reason whereas Christianity says Christ is Logos, a Greek term which means, among other things, reason, account or logic. We worship a rational God who created a rational universe in which he placed men to whom he granted the gift of reason.
You cannot even use your free will to make the decision because Political Correctness casts grave doubt on the freedom of the will, or denies it altogether.
Between the Christian universe and the anti-Christian universe, there is no way to be objective and dispassionate between the two universes. There is no third universe in which to stand while you make the choice. Either you are a member of one or a member of the other.