It has been said that we live according to possibilities. Nothing can be absolutely sure insofar as everything is imperfect.
The colors I see with my eyes may be a slightly different hue than the colors you see with yours. In extension of that idea, no sensory information can be proven empirically precisely because empirical data is received by the senses.
This concept is even more easily demonstrable concerning the mind and the psyche. There are all ranges of mental disorders. For those who consider themselves normal, they still dream, imagine, experience memory loss and recovery, distorted memory, and all sorts of other interpretations of reality that are continually shown to be subjectively perceived and interpreted.
Therefore we do not live according to certainties but rather strong possibilities. For though some philosophers may drive themselves to utter despair at the impossibility of absolute knowledge, the rest of us find it far easier to accept what we experience because of the high probability that it is reality. The agnostic states that nothing is impossible, only highly improbable. On the same token he says that nothing is sure, only highly probable.
In all this one recognizes that the first principle of human existence is faith. We have faith in the physical world that we depend on for our existence and contextual identity.
This leads to the question: how then can it not be the same in the realm of the spiritual?
We make observations that there is much good in humanity. We also observe that there is much corruption in humanity to the point where, historically, humanity has been bent of the destruction of one’s neighbor and self-aggrandizement. It is highly improbable that this be the intended state of affairs, or even the best evolutionary scenario (though some argue that it is the best evolutionary scenario, it is an intellectual cop-out to say that “what is, is best” for it is contrary to every human inclination). The first principle in the spiritual realm must then be faith in a ‘better’ that is not seen. This stands to reason because ‘better’ is what is desired by all humanity. There is an innate longing for a je ne sais quoi that transcends the corruption of this world. We long for a human spirituality that is both completely human and accessible and also completely spiritual and transcendent. This is Jesus.
When one believes in Jesus as the true God-made-man, then all is completed because the completeness of his life, which is transcendent, dwells in her, and this life is known to be real, because he himself was a human. Unverifiable? If you want to go there, I will show you as I did in the beginning, that the rest of your beliefs are just as unverifiable. Weigh the observed reality with the solution of Jesus against the cry of your soul, and tell me what is more possible: a good world corrupted with nothing to fill the cry of humanity for something better, or a good world corrupted longing for the very thing that it was made to long for; one of it’s own to be all in all for all.