Why did the Jewish religious leaders have to search the Scriptures when Herod asked where the King of Israel would be born?
They had to search the Scriptures because they were ignorant of the precise Old Testament prophecy concerning the Messiah's birthplace. Although the information was available, they hadn't bothered to study deeply, knowing only surface matters. Once they searched, they found He was to be born in Bethlehem.
Les explains that Israel should have known who Jesus was because it was in the Old Testament. They could have known but didn't bother to study. The priests knew the surface things, but not the nitty gritty of the Old Testament prophecies. When the wise men came to Herod asking about the King of Israel, Herod called up the big wigs of Judaism and asked where the King was to be born. They did not know, so they had to search the Scriptures. They found it: He was to be born in Bethlehem. So they could have known, but they didn't.