“This is the message which we have heard from Him and declare to you, that God is light and in Him is no darkness at all.”
John makes his foundational statement for his argument here, very simply: God is light. He makes sure you understand what he is saying by repeating that statement in a different way: in Him is no darkness at all. A clear plain statement so there is no confusion as he builds his lesson about the basis of fellowship with a Holy God.
Think about it; not only are you, as a sinner, condemned to the fires of hell for all eternity, but you can also have fellowship with God and walk with Him. It’s not only available to barely escape eternal death just to fade into the outskirts of the crowd. Eventually every now and again maybe catch glimpses of someone who would pay the ultimate debt for you to live, but you are invited, you are expected to come into that light and commune with the Celebrity of the universe. Fellowship is understood simply as light and darkness and fellowship with God is all about the light.
John cannot make it any more clear, any more simple: light or dark, wrong or right. As you continue in this book, consider yourself and where do you spend your time.