John 1:8

He himself was not the light: he was sent to give witness about the light.

John 1:20

He said quite openly and straightforwardly, I am not the Christ.

John 3:28

You yourselves give witness that I said, I am not the Christ. What I said was, I am sent before the Christ.

Acts 19:4

And Paul said, John gave a baptism which goes with a change of heart, saying to the people that they were to have faith in him who was coming after him, that is, in Jesus.

Treasury of Scripture Knowledge

Summary

He was not that Light, but was sent to bear witness of that Light.

General references

Bible References

That light

John 1:20
He said quite openly and straightforwardly, I am not the Christ.
John 3:28
You yourselves give witness that I said, I am not the Christ. What I said was, I am sent before the Christ.
Acts 19:4
And Paul said, John gave a baptism which goes with a change of heart, saying to the people that they were to have faith in him who was coming after him, that is, in Jesus.

General references

Mark 11:30
The baptism of John, was it from heaven or from men? give me an answer.
Acts 13:24
For whose coming John made ready the way by preaching to all the people of Israel the baptism which goes with a change of heart.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain