en_tn_condensed/jas/02/09.md

if you favor

"give special treatment to" or "give honor to"

committing sin

"sinning." That is, breaking the law.

you are convicted by the law as transgressors

Here the law is spoken of as if it were a human judge. This can be translated using an active verb. Alternate translation: "the law itself convicts you of transgressing it" or "you are guilty of breaking God's law" (See: rc://en/ta/man/jit/figs-personification)