That which claims to answer all questions has no place in Christianity. (Crossroads, p. 6)
1. It was Eunomius, the radical Arian, who claimed to know God as well as God knew himself. Orthodox theology confesses that God dwells in light unapproachable, not merely light unapproached. Hence the importance of the apophatic way in theology: we cannot know God in his essence, but only by his energies--the "back parts" of God, as St. Gregory the Theologian says. The confident Christian apologist who becomes an atheist is, by now, a trope. He has confused his map of the territory for the territory itself. If and when he finds some stubborn fact contradicting his map, he gives up the territory.
2. "Now we know in part," says Paul, and "through a glass darkly." Not only do we not know everything; even the things we know are known murkily, as it were. So the Christian speaks about most things with hesitation, tentatively, with gentleness. Just as the true scientist always has in the background "of course, I may be missing something," so also with Christians on most points. Humility is the watchword.
3. That's not to say we know nothing, or that no questions can be answered. "I determined to know nothing among you--except Jesus Christ and him crucified," says Paul to the Corinthians, the know-it-all community. Christ crucified is surely the heart and soul of all that we know; and if there is any murkiness here, it is not due to the fact, but to our own clouded hearts. We know that God is Father, Son, and Holy Spirit; we know that Christ is God and man; we know that Mary is Theotokos and the answers to many other questions.
4. The content of the message shapes the character of the messenger. There's an episode of Fawlty Towers where Basil is prepared to do a fire drill. Neither he nor the guests believe there is actually a fire, and so their attitude is nonchalant. But then a fire does break out in the kitchen. Manuel steps out of the kitchen. His message is the same as Basil's: "Fire!" But his demeanour is altogether different. His hair is disheveled, his gaze is intense, his message is clipped and focused. You can see wisps of smoke coming from his hair and his uniform. (The whole clip may be seen at: https://www.youtube.com/watch?v=1IMlhu9fjVI). So when Paul addresses the Corinthians he says, "And I, brethren, when I came to you, did not come with excellence of speech or of wisdom declaring to you the testimony of God. 2 For I determined not to know anything among you except Jesus Christ and Him crucified. 3 I was with you in weakness, in fear, and in much trembling. 4 And my speech and my preaching were not with persuasive words of human wisdom, but in demonstration of the Spirit and of power, 5 that your faith should not be in the wisdom of men but in the power of God."