1 John 2:3 - Coke's Commentary on the Holy Bible

Hereby we do know that we know him— To know Christ, to love him, to have him, and to be in him, are in this epistle used as synonymous terms, or very nearly so. St. John had in the former chapter intimated, that no man can have communion with God, unless he walk in the light, as God is in the light. Here he asserts, that no man can have any benefit from Christ's being an Advocate with the Father, or a propitiation for the sins of men, unless his knowledge of God and the gospel produces holiness of heart and life. This seems to be the connection between the present and the foregoing verse. The false teachers boasted of their knowledge, while their practice was bad; hence they were called Gnosticks;—and that perhaps might be the reason why St. John so often repeats the words know and knowledge. The knowledge of God does not consist in mere opinion, or barren speculation, or in mysterious notions of his nature and essence, but in that practical knowledge which leads to a love of God, and keeping the divine commandments. It has been observed, that there was a set of men, who rose up in the Christian church, even in the days of the apostles, who so far perverted the doctrine of the great apostle St. Paul concerning justification by faith, without the works of the law, as to pretend that they who knew the truth, and had faith, were under no necessity of leading a holy life. All the seven Catholic Epistles seem to have been particularly levelled against that dangerous error, and the present text is a direct confirmation of this opinion. Practical errors are the most dangerous errors; and unless knowledge is carried into practice, and faith influences to a right temper and conduct, our knowledge is vain, and our faith also is vain: but the knowledge of God which influences to a holy experience and a right practice, will, if persevered in, end in eternal life.