3:55 when God said, “O Isa, indeed I will Cause you to die (mutawaffeeka) and raise/exalt you (rafiAAuka) to Myself and purify you from those who disbelieve and make those who follow you [in submission to God alone] superior to those who disbelieve until the Day of Resurrection. Then to Me is your return, and I will judge between you concerning that in which you used to differ.
FIRST PROMISE: When God said, “O Isa, indeed I will Cause you to die (mutawaffeeka)
The Jews wanted to kill Isa and tried to even crucify him and take his life away because Deuteronomy 21:22,23 states that one who dies on the cross is an accursed. God replies to the plan of the Jews by saying they will not be able to kill Isa, God will cause him to die (meaning a natural death) quickly by natural causes not by the cause of crucifixion.
SECOND PROMISE: And raise/exalt you (rafiAAuka) to Myself
Meaning Isa will be raise/exalt in status towards God just like other believers and things raised/exalted in status towards God in the Quran. 43:32, 94:4, 6:83, 19:57, 6:165, 7:176, 56:3, 35:10, 24:36.
THIRD PROMISE: Purify you from those who disbelieve
This means that God will clear him of the false charges from the enemies such as legitimacy of birth and accursed death and would show that he was indeed a true Prophet of God.
FOURTH PROMISE: And Make those who follow you [in submission to God alone] above to those who disbelieve until the Day of Resurrection
This basically means that precedence would be given to the followers of Isa those believers who followed him when he was alive and those who will follow his message of submission to God alone over the disbelievers till the Day of Judgment. (Muslims are of course included in the believers because they follow submission to God alone and believe in Isa as a Prophet/Messenger of God).