Albert Barnes Commentary 1 John 5:11

"And the witness is this, that God gave unto us eternal life, and this life is in his Son." — 1 John 5:11 (ASV)

And this is the record. This is the sum, or the amount, of the testimony (marturia) which God has given concerning him.

That God has given to us eternal life. He has provided, through the Saviour, the means of obtaining eternal life (John 17:2; John 17:3).

And this life is in his Son. It is treasured up in him, or is to be obtained through him (John 1:25; John 14:6; Colossians 3:3).

The term "record" here can also be understood as "witness." The phrase "this life" is connected with John 1:4.