I imagine you want a simpler, more direct answer, *Tolerance*.
God created all people. And He wanted to hang out with them. It went sour pretty quickly with Adam and Eve, and just got worse. People all over the place started inventing their own ideas of who created them (Much as we do today) and were "worshiping" everything from imagined monsters, to rocks and trees.
So God pulled one man out of all this confusion, and had a conversation with him. (actually, several conversations) This was Abraham. Up to that time Abe also worshiped some of the weird gods. In fact, his own father crafted idols for people to worship.
But (and this is key in understanding the most important part of why Jesus eventually came.), God wanted them to remember who He really was. So ............
God made a deal with Abe, that his children would be protected from the other inhabitants of the Earth, and blessed with good health, good land, lots of crops, and big families, etc..... IF they honored only Him , and followed a few simple rules.
Again, just like with Adam and Eve, what with us being the stubborn humans we are, that didn't last too long, either.
The Bible is, basically, a history book of all the many times the Israelites (the people God chose through Abraham) kept fouling things up... and God kept forgiving, and making new deals with them, while they kept on messing up.
Time rolls on, and the religion the Israelites developed, Judaism, repeated the same thing the original people had done. They got God completely confused in their minds.... making something out of Him, and their religion, that was almost as foreign to the true God who created them as what the pagans had invented for themselves.
So.... Jesus comes, saying "This is what God REALLY looks like... turn back to recognizing Him,"
But the Jews had really gotten into this religion they had altered, rearranged, and reconstructed. They worshiped it almost AS their god. It was now so completely different from this "rhetoric" Jesus was espousing, that they wanted none of it, honestly believing the things Jesus said to be heretical lies.
The rest, you pretty well know. They got rid of Jesus, and kept right on worshiping Judaism instead of Jesus' clarification of God.
That's about it. EXCEPT for the fact that we "Christians" have been repeating the cycle for almost 1,800 years, and it is getting pretty bad again. The early church listened to Jesus, and they "got it." But we are now doing to Christianity, what the Israelites did to Judaism.
Who knows where this latest version of stubborn "reinventing" of Jesus' Father will lead us?