Final answer:
According to John 4:20, our ancestors, likely referring to the Samaritans, worshipped on Mount Gerizim, which contrasts with the Jewish belief of worshipping in Jerusalem.
Step-by-step explanation:
Understanding John 4:20
Regarding what our ancestors did on "this mountain," as referred to in John 4:20, the passage pertains to a conversation between Jesus and a Samaritan woman. The 'mountain' mentioned is likely Mount Gerizim, where the Samaritans had their own temple and where they performed their rites, in contrast to the Jerusalem temple where the Jews worshipped.
This question is connected to the conflict between Samaritans and Jews about the correct place of worship. The ancestors of the Samaritans worshiped on this mountain, while the Jewish people claimed that Jerusalem was the appropriate place to worship God. The discourse between Jesus and the woman reflects on the broader theme of worship and divine revelation.