This is the message which we have heard from him and announce to you, that God is light, and in him is no darkness at all.

 Every man, when he sits down to write a letter or rises to preach a sermon, has some object in view. He wishes to produce some effect in the minds and hearts and lives of those to whom his message is addressed. And here at the very beginning of his letter John sets down his objects in writing to his people. 