E
The purpose of the first chapter of 1 John was to compare the truth of God to the error of gnosticism. John was addressing the Gnostics, who were deceived by their own teaching. He wanted the Gnostics to understand that what they believed conflicted with what God said. He was not, however, addressing believers.
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In chapter one, John uses the term WE, "If we say we have no sin" thus he had to be talking to believer as well as the non believing gnostics who did not think they had any sin,