Now this is an interesting question? "Is William Barclay an esteemed scholar recognized by main stream Christianity, or are his views considered heretical in many ways?
Personally, I would not consider him an esteemed scholar. I base this on the fact that after reading about him I find him to be a "double-minded" man as noted by the Apostle James at James 1:8.
The Bible says, "A double-minded man is unstable in all his ways." A double-minded is "having in the mind opposite or opposing views at different times." To be double-minded is to be inconsistent, vacillating, to be and act one way today and be and act some other way tomorrow.
So, as you know you quoted Professor Barclay in support of the fact that the speaker at Revelation 22:12-13 cannot be specifically identified with the implication that Jesus Christ is not God.
I researched Professor Barclay and provided proof/evidence that he believed Jesus Christ is God. Since you consider yourself a Christian do you recognize or deem Professor Barclay a Christian and are his views considered heretical in any way?
Some new information has come to light which confirms my belief that Professor Barclay is a double-minded man. It is also stated by the Jw's that Barclay did not believe in the preexistence of Jesus Christ and that Jesus Christ was a created being.
The following is from Barclay's commentary on John chapter 1 here. https://www.studylight.org/commentaries/dsb/john-1.html What Barclay said.
"The word was already there at the very beginning things. John's thought us going back to the first verse of the Bible. "In the beginning God created the heavens and the earth" (Genesis 1:1). What John is saying is this--the word is NOT ONE OF THE CREATED THINGS; the word WAS THERE BEFORE CREATION; the word is not part of the world which came into being in time; the word is part of eternity and was there with God before time and the world began. John was thinking of what is known as the preexistence of Christ."
Barclay goes on to say in the next paragraph these words, "If God's word is part of the eternal scheme of things, it means that God was always like Jesus." Now, I'm not going to dispute that Barclay did not believe Jesus was God, but when you read what he writes he sure "implies" it without actually saying it. Denying the deity of Jesus Christ means one is lost. John 8:24, "I said therefore to you, that you shall die in your sins; for unless you believe I am, you shall die in your sins."
I think it is important to fact check everything with Acts 17:11 in view, and that includes me.
The following is what Professor Barclay said about Revelation 22:12-13. THE CLAIMS OF CHRIST (Revelation 22:12-13) https://www.studylight.org/commentaries/dsb/revelation-22.html
"22:12,13 Behold, I am coming soon, and I have my reward with me, to render to each man, as his work is. I am Alpha and Omega, the first and the last, the beginning and the end.
The Risen Christ once again announces his speedy coming; and he makes two great claims.
(i) He has his reward with him and will render to every man according to his work. H. B. Swete says: "Christ speaks as the Great Steward, who in the eventide of the world will call the labourers to receive their day's wages."
(ii) He is Alpha and Omega, the first and the last, the beginning and the end. This is a repetition of titles used in Revelation 1:17; Revelation 2:8; Revelation 21:6. There is more than one idea here.
(a) There is the idea of completeness. The Greeks used from alpha (Greek #1) to omega (Greek #5598) and the Hebrews from aleph to tau to indicate completeness. For instance, Abraham kept the whole Law from aleph to tau. Here is the symbol that Jesus Christ has everything within himself and needs nothing from any other source.
(b) There is the idea of eternity. He includes in himself all time, for he is the first and the last."
Finally, I did make the following statement? "I'm not going to dispute that Barclay did not believe Jesus was God, but when you read what he writes he sure "implies" it without actually saying it."
Since Professor Barclay does indeed deny the deity of Jesus Christ I apologize for not doing "due diligence" in my research. There is one last thing I would like to comment on. The word "Trinity" has been brought up by some on this issue. I am not here to prove the Trinity, I am here to address the question, "Who is Jesus Christ."
Personally, (and I've said this for many years now), I don't believe Trinitarianism is a REQUIREMENT for salvation. It is the RESULT of salvation, for you cannot know Jesus and somehow miss the fact that He is God. You cannot have experienced the presence of the Holy Spirit of God and somehow miss that He is God. Romans 8:9-11