Charles Spurgeon Commentary 1 John 2:4-6

"He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him; but whoso keepeth his word, in him verily hath the love of God been perfected. Hereby we know that we are in him: he that saith he abideth in him ought himself also to walk even as he walked." — 1 John 2:4-6 (ASV)

He that saith, I know him, and keepeth not his commandment, is a liar, and the truth is not in him. But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him. He that saith he abideth in him ought himself also so to walk, even as he walked. (1 John 2:4–6)

When we try to be, in every respect, what God's Word tells us we ought to be, then may we know that we are in God; but if we walk carelessly, if we take no account of our actions, but do, after a random fashion, whatever comes into our foolish hearts, then have we no evidence at all that we are in God.