5 Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the LORD:
6 And he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.
I have always believed that "the fathers" are the Jews and "the children" are the Christians.
The children could be 'the gentiles' since the Israelites were to be a linght unto the nations, and nations meant gentiles, and the gentiles were supposed to be grafted unto the Jews.
Why? Can you not see that in this day and age, in our culture of unfettered sexual activity, men are impregnating women they don't know, and don't care about....and pay to have their children killed in the womb. They have no heart for their children. And if their children survive the womb, then they grow up hating the father who has little to do with them...
I take this verse literally.