That’s not true at all. There was faith in the savior before Christ came. Just look at the story of Abraham. He knew that God would provide “the lamb” for the sacrifice. That’s why the Bible says Abraham believed in God, and it was accounted to him for righteousness. Many Old Testament people had this same faith.
That's not how I read it. To me it's pretty clear that the God of the Old Testament was a pretty scary dude. If He says sacrifice your son, you'd better comply. Or else.
Abraham took his son to the alter in terror and grief, not in a certainty of redemption.
Only then, after He had made His point, did God show mercy.
Have you no sense of history? It's only been a little over a century since the "best" Christians were described as "God Fearing Christians". God Fearing, not the current namby-pamby theetie-wheetie God is love, and all forgiving form of Christianity.