1 John 5:10

Having spoken of the character of the divine witness to Jesus (1 John 5:6-9), John moved to discuss the results of that witness (1 John 5:10-12). The witness is the truth about Jesus Christ that the indwelling Holy Spirit bears. This may be the objective witness of Scripture, or it may be a subjective witness in the believer’s heart. The Spirit witnesses in both ways. If someone does not believe this testimony, he is saying that God has lied (cf. 1 John 1:10). John clarified the implications of rejecting the gospel in stark terms.

"The writer, then, cannot allow that one can profess belief in God, as did his opponents, and yet reject God’s testimony to his own Son. Such rejection cannot be excused on the basis of ignorance. The evidence is too clear and too weighty. Rather, it is deliberate unbelief, the character of which in the end impugns the very being and character of God. If Jesus is not God’s own Son in the flesh, then God is no longer the truth. He is the liar." [Note: Barker, p. 352.]

Believing in the Son of God is the same as believing that Jesus is the Christ (cf. 1 John 5:1; John 3:15-16; John 3:18; John 20:30-31).

"There is nothing here about ’head or heart belief,’ or about a ’faith that yields to God as over against mere intellectual assent,’ etc. The Bible does not complicate faith like that. Once we have understood the message, the issue is: Is it true or false? Do we believe it, or do we not?" [Note: Hodges, The Epistles . . ., p. 224.]