1 John 2:3-6 RSVA

3 And by this we may be sure that we know him, if we keep his commandments.
4 He who says "I know him" but disobeys his commandments is a liar, and the truth is not in him;
5 but whoever keeps his word, in him truly love for God is perfected. By this we may be sure that we are in him:
6 he who says he abides in him ought to walk in the same way in which he walked.