Gr. martureō, “to witness,” “to bear witness.” Martureō and marturia occur 10 times in the genuine text (see on v. 7) of vs. 6-11. The form of the Greek verb indicates that the reference is to God’s past witness, the effect of which is still continuing.

Gr. marturia, “witness.” Compare the verb martureō, “to witness” (see below under “gave”).

Literally, “because he hath not believed.” A clear restatement of the specific form of disbelief of which the rejectors of Christ’s divinity are guilty. John thus lays bare the ultimate nature of all disbelief.

Not that man can make God lie, but he makes Him out to be a liar by affirming that what God has witnessed is not true.

 One might have expected John to say, “believeth not on the Son of God,” as the negative of his preceding statement, but the apostle goes deeper, since he knows that refusal to accept the Father’s witness concerning His Son is a refusal to believe God (cf. ch. 2:22, 23). In his penetrating way John has analyzed the ultimate nature of all disbelief—it rejects even the Father.

He who actively believes on Jesus will have an inner witness to the validity of that belief. He will know, by personal experience, that Jesus is all that the Scriptures claim Him to be. Such belief is not easily overthrown: it is capable of withstanding the worst attacks the enemy can bring.

 At the same time it should be remembered that it is dangerous to trust solely on inner feelings as to our relationship with God. While there will often be times when we feel confident of our fellowship with the Lord, there will also be days of doubt. It is in such times that the Lord has promised to be especially near to His children (Isa. 43:2). We should therefore hold to our connections with God even when feelings dictate otherwise. The Christian life should be based upon principle rather than feeling (1T 167). As faith grows stronger, the witness within our hearts grows stronger, too (1 John 3:24).

 Gr. eis, “unto,” “into.” John uses this particular preposition with the word for “believe” more frequently than all the other NT writers together. Such belief is a personal approach to Christ in firm reliance upon the truth of God’s testimony, and a consequent trust in the Saviour’s redemptive work (cf. on John 1:12).

That is, the one who is continually believing Christ to be the Son of God. One who has a fluctuating, transitory conviction cannot claim or invalidate this promise.