Let’s face it – it’s tough for anyone to believe that Jesus could be fully God and Man at the same time. But however impossible it might be to understand, we have the best of reasons to believe it’s true: the testimony of the Spirit, the water and the blood. At the time of Jesus’ baptism, the Spirit descended on Him like a dove, as He rose from the waters. And God the Father also spoke about Jesus at the same time, saying from Heaven, “This is My beloved Son, in Whom I am well pleased” (Matthew 3:16-17). No, there can be no doubt that Jesus was truly the Son of God.

Well, what about His humanity? At the end of Jesus’ life, the water and blood also proved that Jesus was fully human, as both of them poured out of His side when a Roman soldier pierced Him with a spear (John 19:34). Meanwhile, God bore witness as the light of the sun was blotted out for three hours, there was a great earthquake, and the curtain of the Temple was torn in two from top to bottom (Matthew 27:45, 51). No, we can have no doubt that the Son of Man died on the cross, paying the death penalty all our sins deserve.

So yes, we have every good reason to believe that Jesus was fully God and fully Man at the same time. And it is important for us to believe this. After all, in verse 10, John reminds us that since God has made His identity so clear, if we were to reject the claims of Christ we would be calling God a liar. And verse 12 says that would mean cutting ourselves off from the only true source of light and life.

But believing in Jesus, trusting Him as Savior and bowing the knee to Him as Lord, also brings us great benefits. For if Christ is within us, we can be sure we have eternal life (v. 11). Moreover, when we trust in Jesus, we rely not only on all the Biblical and historical evidence of His identity. Because He lives within us in His Holy Spirit, we also have the testimony, the certainty of the claims of Christ in our hearts as well (v. 10).

So, let’s believe all these reliable witnesses, and let’s rejoice that the Son of God and the Son of Man has sacrificed Himself so that we might be saved.

I John 5:1-21 (ESV)

Everyone who believes that Jesus is the Christ has been born of God, and everyone who loves the Father loves whoever has been born of him.
2 By this we know that we love the children of God, when we love God and obey his commandments.
3 For this is the love of God, that we keep his commandments. And his commandments are not burdensome.
4 For everyone who has been born of God overcomes the world. And this is the victory that has overcome the world– our faith.
5 Who is it that overcomes the world except the one who believes that Jesus is the Son of God?
6 This is he who came by water and blood– Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth.
7 For there are three that testify:
8 the Spirit and the water and the blood; and these three agree.
9 If we receive the testimony of men, the testimony of God is greater, for this is the testimony of God that he has borne concerning his Son.
10 Whoever believes in the Son of God has the testimony in himself. Whoever does not believe God has made him a liar, because he has not believed in the testimony that God has borne concerning his Son.
11 And this is the testimony, that God gave us eternal life, and this life is in his Son.
12 Whoever has the Son has life; whoever does not have the Son of God does not have life.
13 I write these things to you who believe in the name of the Son of God, that you may know that you have eternal life.
14 And this is the confidence that we have toward him, that if we ask anything according to his will he hears us.
15 And if we know that he hears us in whatever we ask, we know that we have the requests that we have asked of him.
16 If anyone sees his brother committing a sin not leading to death, he shall ask, and God will give him life– to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that.
17 All wrongdoing is sin, but there is sin that does not lead to death.
18 We know that everyone who has been born of God does not keep on sinning, but he who was born of God protects him, and the evil one does not touch him.
19 We know that we are from God, and the whole world lies in the power of the evil one.
20 And we know that the Son of God has come and has given us understanding, so that we may know him who is true; and we are in him who is true, in his Son Jesus Christ. He is the true God and eternal life.
21 Little children, keep yourselves from idols.