Jesus is fully God and fully man. He had two natures while here on earth. The Trinity fits all scripture. You can not find any verse that this doctrin does not fit. We believe in one God existing in 3 persons. One what and three whos. Jesus is the begining and ending, the alpha and omega, he who was, who is, who is to come. The Almighty.
Phil 2:5-11
5 Let this mind be in you which was also in Christ Jesus,
6 who, being in the form of God, did not consider it robbery to be equal with God,
7 but made Himself of no reputation, taking the form of a bondservant, and coming in the likeness of men.
8 And being found in appearance as a man, He humbled Himself and became obedient to the point of death, even the death of the cross.
9 Therefore God also has highly exalted Him and given Him the name which is above every name,
10 that at the name of Jesus every knee should bow, of those in heaven, and of those on earth, and of those under the earth,
11 and that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
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There is only one true God
John 17:3
3 "This is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent.
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I Jn 5:20
20 And we know that the Son of God has come, and has given us understanding so that we may know Him who is true; and we are in Him who is true, in His Son Jesus Christ. This is the true God and eternal life.
(NAU)
If Jesus is not the true God then Thomas was wrong and Jesus would have told him so.
John 20:28-29
28 Thomas answered and said to Him, "My Lord and my God!"
29 Jesus said to him, "Because you have seen Me, have you believed? Blessed {are} they who did not see, and {yet} believed."
(NAU)