This expression strongly denies that this could happen. You may have an expression in your language that you could use here. "That is not possible!" or "Certainly not!"
God will always be true and will keep his promises. Alternate translation: "God always does what he has promised" (See: [[rc://en/ta/man/translate/figs-explicit]])
The words "every" and "liar" are exaggerations here to add emphasis that God alone is always true to his promises. Alternate translation: "even if every man were a liar" (See: [[rc://en/ta/man/translate/figs-hyperbole]])
You can translate this in an active form. Alternate translation: "The Scriptures themselves agree with what I am saying" (See: [[rc://en/ta/man/translate/figs-activepassive]])
These two phrases have very similar meanings. You can translate this in an active form. Alternate translation: "Everyone must acknowledge that what you say is true, and you will always win your case when anyone accuses you" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-activepassive]])