Substitutionary Atonement

I'm appreciating the substitutionary atonement of Jesus all over again after today's sermon. Abraham was prepared to sacrifice his son Isaac but God provided a substitute. I always read the Abraham story and say "phew! glad he didn't have to do it." But God actually did let the sacrifice of His own Son be carried out, and not only that but He poured all the unjust sins of humanity upon the one purely righteous person ever to walk the earth. I understand why people don't want that to be the case. The enormity of it hits you like a ton of bricks, when you imagine having to watch your own child die in front of you. Then imagine you have the power to stop it, you have the gun to the guy's head that's about to kill your child, but to save that guy, you will let him kill your son. That's what's so enormous about it, that He didn't have to do it. He was perfectly just in letting us to our own fate after choosing the knowledge of Good and Evil, but He didn't leave us. He sent provided a way for forgiveness and salvation, if we only decide to accept the freely given sacrifice and resurrection of His Son for our sins. Remarkable.