Whosoever committeth sin— St. John's design in this verse, was not to explain the meaning of the word sin, but to assure the Christians that sin exposed a man to punishment; and then the connection is clear and evident: 1 John 3:3. "He that hopes for the heavenly felicity, purifies himself even as Christ is pure: 1 John 3:4. He who defiles himself with vice or wickedness, must be miserable; for wickedness will expose a man to punishment: 1 John 3:5. For this great and gracious purpose was Jesus Christ manifested, that be who had no sin of his own, might take away our sin, and free us from the punishment of the wicked and impenitent." See ch. 1 John 5:17.
Related Commentaries of 1 John 3:4
1 John 3:4
4 Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law.