That would bring Islamic fanatics from all over the world with bombs strapped to their bodies. 3 million migrants just entered with no vetting. There are many more Muslims in the world than Christians. And they are present in 150 countries all over the world.
Better foreign policy would be to stay out of foreign wars. Let the dictators like Saddam Hussein control the fanatics locally. He kept fanatics subdued and in jail.
If Mecca was gone, Islamics would realize that their Allah could not even protect his own “holy” city. Islam would fade away.