Doubters want evidence that there is a God. The Almighty has given mankind three powerful witnesses to affirm His existence. It is up to each person as to whether or not they will believe the testimony of these witnesses.
It seems that too many Christians live joyless lives of drudgery and worry. Certainly, we have our times of trouble and grief, but what of the joy in being a Christian? Scripture states that one reason Jesus could endure the cross was because of "the joy set before Him." What's that all about? And does it mean anything for the Christian?
John's third letter is a "snapshot" of early Christian life. Some in the church were living the truth of God, and some were not. It shows people have not changed. And this unchanging life principle was holding true: Love is not demonstrated by what a person believes or by what they know, but by what they do.