This is how we know that we know him: if we keep his commandments.
But we are not hence to conclude that faith recumbs on works; for though every one receives a testimony to his faith from his works, yet it does not follow that it is founded on them, since they are added as an evidence. Then the certainty of faith depends on the grace of Christ alone; but piety and holiness of life distinguish true faith from that knowledge of God which is fictitious and dead; for the truth is, that those who are in Christ, as Paul says, have put off the old man. (Colossians 3:9.) 