Faith in Matt 23 is a duty of the Law Matt 23:23I mean Faith necessary for Salvation. In the Scripture you quoted "judgement, mercy, faith" are not works of the Law but rather moral righteousness.
23 Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone.