Mount Gerizim was the worship center of the Samaritans (Jews who had intermarried with Gentiles and where thus excluded from the temple in Jerusalem). They believed that this mount, rather than the one in Jerusalem, was the mountain God chose for worship. The Samaritan woman addressee this issue with Jesus in John 4:20.
A temple was built there in 4th century B.C. which was destroyed in 107 B.C.
Just before the Israelites were brought into their promised land, Moses had the tribes of Israel that were to give blessings stand on Mount Gerizim, while the tribes who were to pronounce curses stood on Mount Ebal (Deuteronomy 27:11–13). These were blessings and curses promised them for obeying or disobeying the Lord, given in Deuteronomy 11:25–30.
Also, in Judges 9:7, Jotham (the brother of Abimelech and the son of Gideon) climbed Mount Gerizim to shout a proclamation to the people of Shechem for crowning Abimelech king after Abimelech had killed his 70 brothers.
