Charles Ellicott Commentary John 17:3

"And this is life eternal, that they should know thee the only true God, and him whom thou didst send, [even] Jesus Christ." — John 17:3 (ASV)

And this is life eternal.—These words are more frequent in Saint John than in any other New Testament writer (John 3:36; John 5:24; John 5:39; John 6:27; John 6:40; John 6:47; John 6:54; John 6:68; John 10:28; John 12:25; John 12:50; 1 John 1:2; 1 John 2:15; 1 John 3:15; 1 John 5:11; 1 John 5:13; 1 John 5:20).

The previous verse indicates that Christ's Messianic work is to give eternal life to those whom God has given Him. The following verse states that He has accomplished this work. This present verse shows in what its accomplishment consists—namely, in revealing to humanity the only true God through Jesus Christ.

That they might know You the only true God.—A better rendering is, That they might recognize You as the only true God. (Compare Notes on John 1:9; John 14:7.)

And Jesus Christ, whom You have sent.—A better rendering is, And Him, whom You sent, Jesus, as Messiah.

Eternal life consists in the knowledge of the Father as the only Being who corresponds to the ideal conception of God, and in this knowledge as it is manifested in Him whom God anointed and sent into the world to declare His attributes and character.

Only in the Word made flesh can we hear the voice of mercy, forgiveness, love, and fatherhood—a voice which comes to humanity as the breath of life, so that they become living souls.