Charles Ellicott Commentary John 20:28

"Thomas answered and said unto him, My Lord and my God." — John 20:28 (ASV)

Thomas answered and said unto him.—It is implied that he did not make use of the tests which his Master offered him, but that he at once expressed the fullness of his conviction. This is confirmed by the words of the next verse, Because thou hast seen Me.

My Lord and my God.—These words are preceded by said unto him, and are followed by because thou hast seen Me, thou hast believed; and the words my Lord can only be referred to Christ. (Compare to John 20:13.) The sentence cannot therefore, without violence to the context, be taken as an exclamation addressed to God, and is to be understood in the natural meaning of a confession by the Apostle that his Lord was also God.