Depends on how you believe. Many instances when Yashua was representing the Father, this was one of them. He states, "if you have seen me, you have seen the Father."
I look so much like my mother that people have said I could pass for her. Does that mean I am her? No, I represent what she looked like.
Yashua constantly states the Father is the authority.
Yashua did exist before Abraham, but the bible tells us that Yahweh always existed, not Yashua.
Of course he forgives sin, by the author His Father Yahweh.
Matthew 28:18 ...All authority has been given to me in heaven and on earth.
"Given to me", not that as the Father I have that power
Questions
If they are the the same one;
1. Why does Yashua say only the Father knows when the end is ?
2. Is Yahweh not really His father as He was conceived by the Holy Spirit?
3. Yashua was praying to Himself in the garden when he asked if this cup could be passed by Him?
4. When dying on the cross and he cried, "my Elohim my Elohim why have you forsaken me?" He was talking to Himself?
5.If They are the same, then Yashua raised Himself from the dead? Then if He did, He didn't really die as a dead person cannot raise Himself.
As for Thomas, He did not accept or rebuke him. Saying He did, is just your interpretation of it. He did say, you believe because you have seen, blessed are they who believe and have not seen.
John 20:31 - But these are written, that ye might believe that Yashua is the Messiah, the Son of Yahweh; and that believing ye might have life through his name.
More verses that states Yashua is the Son of Yahweh.
Mark 1:1
Matthew 16:17
Acts3:13
John 6:68