Tertullian, a Christian Father?

Yes, and I think you have completely misunderstood what he was saying. He was making the point that all the religious groups use Christian symbolism, even if they do not fully understand what it means. The way they portray their Gods points to the true God and the sacrifice of Christ. It is not saying Christianity took those aspects and made them into Christian symbols, it is that the symbols were deliberately allowed to used so that when the complete picture came they could see.