The secret in understanding what is happening (short of spending a few years learning the koine Greek of the Bible and another few years researching manuscripts) is to learn to use several translations. These people have done exactly that. They know the Greek and they know the manuscripts.
On the matter of Rev 1:11-- the KJV and YLT have Jesus calling himself the alpha and the omega.
The NRSVA;NIV;ASV among others DO NOT.
So, what does that tell you? That that passage has, over time, experienced some corruption. Scholars are not in agreement as to the correct rendering. In an argument about the trinity, this has to be left out since it is in question.
As to the references in Isaiah cited by Seven: The fact that the messiah is being referred to as a mighty god and then Jehovah also is referred to as such does not, in any way, even suggest that the two are one let alone establish that as a fact. Peter was an apostle. John was an apostle. Peter and John were not the same person. Angels could, in some context, be properly referred to as gods. This would not make them THE almighty God. The titles 'Lord' are used to refer both to Jehovah and to Jesus. Abraham was referred to as lord. Would that make him Jesus? Would that make him Jehovah? Nope. It's just a title.
Now the society maintains that the title 'alpha and omega' is Jehovah's exclusively. That may very well be the case. BUT even if it were used in connection with Jesus, I would still have no problem with that. In some ways Jesus isthe first and the last. He is Jehovah's first born and the onlybegotten and thus he is, in this respect, the first and the last by virtue of there being no one like him before and none like him afterwards. Neveris Jesus spoken of as being almighty or so much as equal to the father although the scriptures have Jesus stating that the father is greaterthan he is. The father never calls the son 'my god' but the son does speak of the father in such a way. The son dies. The father cannot die. The trinity doctrine says they are 'co-equal and co-eternal' and yet for parts of three days, at the very least, the son did not exist. During that time there could not have been a trinity in existence and therefore the term 'co-eternal' could not be applied to the trinity.
Your turn.