This book claims no author but scholars all agree that it is John. This is written about 20 years after the Temple was destroyed in a Jewish Roman War. The entire Temple Herod built was destroyed leaving the Jews without a center for worship. Since then a Philosophy had really taken root called Gnosticism.
Gnosticism in short said that the human nature consists of 2 parts, flesh and spirit. Sin was in the body only, not the spirit. So basically the spirit dealt with Spiritual matters, while the body could do what it wants. In Gnosticism, people believed in a “mystical” knowledge that some could obtain through knowledge, like a spiritual maturity or epiphanies. (I actually know of someone who is a Gnostic).
Gnostics also denied the incarnation, they said that God was more like a phantom, a man in appearance only (called Docetism). Another theory called Cerinthianism (very large following) believed that Jesus was a normal man and that the spirit of God joined Him at baptism and left him before the death on the Cross. By the way, if you think “theories” are not as strong today, get out of your comfort zone of the Bible Belt and just make conversations with some strangers in airports all around the country. It will shock you, especially todays teens.
John writes this Letter to ALL Christians. The book of John (the Gospel) was written on believing to receive Eternal Life. 1 John is about Knowing we have eternal life. The word KNOW will be used over 30 times in this short letter.
Soooooo have you ever questioned your Salvation?? Read this book to see “If” you are saved and KNOW.