4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.
4 Whoever says, "I know him," but does not do what he commands is a liar, and the truth is not in that person.
4 Whoever says "I know him" but does not keep his commandments is a liar, and the truth is not in him,
4 If someone claims, "I know him well!" but doesn't keep his commandments, he's obviously a liar. His life doesn't match his words.
4 He who says, "I know Him," and does not keep His commandments, is a liar, and the truth is not in him.
4 If someone claims, "I know God," but doesn't obey God's commandments, that person is a liar and is not living in the truth.
Matthew Henry's Commentary on 1 John 2:4
Commentary on 1 John 2:3-11
(Read 1 John 2:3-11)
What knowledge of Christ can that be, which sees not that he is most worthy of our entire obedience? And a disobedient life shows there is neither religion nor honesty in the professor. The love of God is perfected in him that keeps his commandments. God's grace in him attains its true mark, and produces its sovereign effect as far as may be in this world, and this is man's regeneration; though never absolutely perfect here. Yet this observing Christ's commands, has holiness and excellency which, if universal, would make the earth resemble heaven itself. The command to love one another had been in force from the beginning of the world; but it might be called a new command as given to Christians. It was new in them, as their situation was new in respect of its motives, rules, and obligations. And those who walk in hatred and enmity to believers, remain in a dark state. Christian love teaches us to value our brother's soul, and to dread every thing hurtful to his purity and peace. Where spiritual darkness dwells, in mind, the judgment, and the conscience will be darkened, and will mistake the way to heavenly life. These things demand serious self-examination; and earnest prayer, that God would show us what we are, and whither we are going.