Since, then, as reason teaches, we must repose faith in some one of those who have been the introducers of sects among the Greeks or Barbarians, why should we not rather believe in God who is over all things, and in Him who teaches that worship is due to God alone, and that other things are to be passed by, either as non-existent, or as existing indeed, and worthy of honour, but not of worship and reverence? And respecting these things, he who not only believes, but who contemplates things with the eye of reason, will state the demonstrations that occur to him, and which are the result of careful investigation.
And why should it not be more reasonable, seeing all human things are dependent upon faith, to believe God rather than them? For who enters on a voyage, or contracts a marriage, or becomes the father of children, or casts seed into the ground, without believing that better things will result from so doing, although the contrary might and sometimes does happen? And yet the belief that better things, even agreeably to their wishes, will follow, makes all men venture upon uncertain enterprises, which may turn out differently from what they expect.
And if the hope and belief of a better future be the support of life in every uncertain enterprise, why shall not this faith rather be rationally accepted by him who believes on better grounds than he who sails the sea, or tills the ground, or marries a wife, or engages in any other human pursuit, in the existence of a God who was the Creator of all these things, and in Him who with surpassing wisdom and divine greatness of mind dared to make known this doctrine to men in every part of the world, at the cost of great danger, and of a death considered infamous, which He underwent for the sake of the human race; having also taught those who were persuaded to embrace His doctrine at the first, to proceed, under the peril of every danger, and of ever impending death, to all quarters of the world to ensure the salvation of men?
Source: Against Celsus (New Advent)