Jesus needed to come, because God set the world up so that man would fall, when man falls they will either fall for good and be destroyed or they will be saved. Problem is, once we fell we could never save ourselves. Hence all the sacrifices in the OT pointing to a perfect sacrifice to come.
Since I believe Jesus and God are one and the same, it harmonizes perfectly with the bible in that only God could actually save us. So God in order to show his love for us, took on human form and experienced our pain and punishment for us.
To complicate things more, Jesus did all the suffering and payment BEFORE the world was ever created, and when he came in AD/BC time period it was just a demonstration of what he had already done before the world began. That is completely supported from the language of the bible. There is NO church zero zilch that teaches that, as they are mostly bound by their dogma and theology.
In fact, Abraham or anyone from the OT could not have been saved if Jesus hadn't died before the world began. Salvation is the same for them as it is when Jesus came and demonstrated what he had already done.
Anyway, off topic, but there you go...