The people to whom God has made promises are spoken of as if they were to inherit property and wealth from a family member. (See: [[rc://en/ta/man/translate/figs-metaphor]])
The words "the promise came" are understood from the first phrase. You can translate this by adding these implied words. AT: "but the promise came through faith, which God considers as righteousness" (See: [[rc://en/ta/man/translate/figs-ellipsis]])
Here "live by the law" refers to obeying the law. AT: "if those who obey the law are the ones who will inherit the earth" (See: [[rc://en/ta/man/translate/figs-explicit]])
This can be restated to remove the abstract noun "trespass." AT: "no one can break the law" or "it is impossible to disobey the law" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])