What was the Mount Gerizim worship really?
It was a counterfeit, man-made religion—a secondary Temple worship set up by the northern kingdom Israelites. God's presence was not in it, and they failed to recognize Jerusalem as the headquarters of God's dealing with Israel, so it was not the true worship of God.
Les explains that the northern kingdom Israelites set up a secondary Temple worship on Mount Gerizim as their own counterfeit. The presence of God was not in it; it was just another man-made religion. They headquartered their religion there and did not recognize that God was dealing with Israel through the Temple in Jerusalem. Les points out that all through Israel’s religious history, Jerusalem is the headquarters of God’s operation. By contrast, the New Testament Church has no earthly headquarters—it is headquartered in heaven. Even Antioch, though a fountainhead for the Gospel to the Gentiles, is never named the headquarters of the Church. Under Judaism, Jerusalem was where God dealt with His people. The Samaritans asked what the difference was, and God had to show Samaritan believers that Jerusalem was the headquarters of God’s dealing with the nation of Israel.