Was there actually a historical Jesus? This question is a common source of doubt for many believers. Did this man really exist or is He a myth created to teach us how to be good people? John’s testimony carries weight and authority because of his firsthand encounters with Jesus. He was there with Jesus during most of His ministry. He saw it all. His letter isn’t full of instructions John made up on his own; he’s just passing on what he’s witnessed so his audience can come to know the same joy he possesses.