This is stated in a negative way to emphasize the slaughter. It can be stated in positive form. Alternate translation: "let us kill every one of them" (See: [[rc://en/ta/man/translate/figs-litotes]])
Here "approaching God" is associated with asking him counsel. Alternate translation: "Let us ask God what we should do" (See: [[rc://en/ta/man/translate/figs-metonymy]])