do you hear people say 'my God' all the time in every day life?

though thomas was indeed expressing shock and delight to His God, the Father in heaven, and His Lord, the risen Jesus standing in front of him.

just like paul writes in almost every letter, greetings from God the Father and Our Lord Jesus, always referring to them as two separate beings, and rarely mentioning the Holy Spirit in the greetings and endings of his letters.