en_tn/deu/10/16.md

circumcise the foreskin of your heart

Moses is referring to a spiritual circumcision. This means the people must remove the sin from their lives. (See: rc://en/ta/man/translate/figs-metaphor)

God of gods

AT: "the supreme God" or "the only true God"

Lord of lords

AT: "the supreme Lord" or "the greatest Lord"

the fearsome one

AT: "the one who causes people to fear"