What are two major purposes for John's writing of 1 John?

This was a letter of encouragement and warning to Christians about love. John describes God's love in detail throughout the letter, and he encourages Christians by letting them know the depth of God's love for them. He also warns Christians to be careful about loving the things in the world and desiring things that lead to sin. It can be summed up as a letter instructing the right way to have love by imitating God's love, and the need to avoid loving the wrong things.