What the truthful words of those 2 verses 1 John 5:7 & 8 show is 1. doctoring of them via many and 2. the Trinity crowed and most non trinity said Christians do not have clue as to what they are saying.
Had they done, they would then realize the truth of John 1:1-18. And that being, the Only reference to Jesus (not there) in the first 13 verses is, He is in fact not mentioned and still the hidden mystery, plan within God until he suddenly appears in 1:14 as the Temple where God the Almighty = Spirit/Word/Light is dwelling = Immanuel God with Jesus, but God Not being Jesus. As per Mal 3:1 says, John at first would be preparing the way, making path straight = Truth of who and what was and known = Almighty God and Father who is Word -> The Word, who has a plan, life within himself, in this plan.
You mention the Qur'an, and one reference, and to me, NO that is not screaming that the entire Qur'an, is the word of God.
In OT times, it would seem the Door to the House, God was closed and the plan was, when the times were fulfilled another Door, person would become The Door and Cornerstone to this House, Kingdom, God and from then on, there was, is, no need for anymore prophets and each if they seek the Truth to find the Door, they will also find, be given the Keys to it.
