But if you will have us to meet the most ridiculous among the charges of Celsus, listen to him when he says: “Now God, being unknown among men, and deeming himself on that account to have less than his due, would desire to make himself known, and to make trial both of those who believe upon him and of those who do not, like those of mankind who have recently come into the possession of riches, and who make a display of their wealth; and thus they testify to an excessive but very mortal ambition on the part of God.” We answer, then, that God, not being known by wicked men, would desire to make Himself known, not because He thinks that He meets with less than His due, but because the knowledge of Him will free the possessor from unhappiness.
Nay, not even with the desire to try those who do or who do not believe upon Him, does He, by His unspeakable and divine power, Himself take up His abode in certain individuals, or send His Christ; but He does this in order to liberate from all their wretchedness those who do believe upon Him, and who accept His divinity, and that those who do not believe may no longer have this as a ground of excuse, viz., that their unbelief is the consequence of their not having heard the word of instruction.
What argument, then, proves that it follows from our views that God, according to our representations, is “like those of mankind who have recently come into the possession of riches, and who make a display of their wealth?” For God makes no display towards us, from a desire that we should understand and consider His pre-eminence; but desiring that the blessedness which results from His being known by us should be implanted in our souls, He brings it to pass through Christ, and His ever-indwelling word, that we come to an intimate fellowship with Him. No mortal ambition, then, does the Christian doctrine testify as existing on the part of God.
Source: Against Celsus (New Advent)