Tertullian

“ I may use, therefore, the opinion of a Plato, when he declares, “Every soul is immortal.” I may use also the conscience of a nation, when it attests the God of gods. I may, in like manner, use all the other intelligences of our common nature, when they pronounce God to be a judge. ”

“ Part company with the heathen, O heretic! for although you are all agreed in imagining a God, yet while you do so in the name of Christ, so long as you deem yourself a Christian, you are a different man from a heathen: give him back his own views of things, since he does not himself learn from yours. Why lean upon a blind guide, if you have eyes of your own? Why be clothed by one who is naked, if you have put on Christ? Why use the shield of another, when the apostle gives you armour of your own? ”

“ He, therefore, will not be a Christian who shall deny this doctrine which is confessed by Christians; denying it, moreover, on grounds which are adopted by a man who is not a Christian. Take away, indeed, from the heretics the wisdom which they share with the heathen, and let them support their inquiries from the Scriptures alone: they will then be unable to keep their ground. For that which commends men’s common sense is its very simplicity, and its participation in the same feelings, and its community of opinions ”