en_tn_condensed/deu/13/02.md

comes about

"takes place" or "happens"

of which he spoke to you and said, 'Let us go after other gods, that you have not known, and let us worship them,'

"and he tells you to serve and worship other gods which you have not known,"

Let us go after other gods

"Let us follow other gods"

go after other gods, that you have not known

The phrase "gods, that you have not known" refers to the gods that other people groups worship. The Israelites know Yahweh because he has revealed himself to them and they have experienced his power.