Faith can never be mingled with works especially the works of the Mosaic Law-like circumcision, tithing, Sabbatarianism, food laws and the like. For if it does-grace will be no longer grace.
Faith is just a hand that holds onto its Savior. It is human hand, But It must be also an a empty hand. Either we can save ourselves and do something-or we cannot. If we cannot-then someone must do it for us. That is the essence of faith.