Christ is one of the names of the Lord. It derives from Greek, and means "the anointed one," a King or Messiah. Christ as King brings to mind the infinite Divine truth, while Jesus as savior brings to mind the infinite Divine mercy and love. Together they mean both of these qualities conjoined and so bring to mind the very essence of the Lord.

(सन्दर्भ: Apocalypse Revealed 520 [1,2,3]; Arcana Coelestia 1999 [2], 3004, 3005, 3006; True Christian Religion 298)

520. And there were loud voices in heaven, saying, "The kingdoms of this world have become the kingdoms of our Lord and of His Christ, and He shall reign forever and ever!" This symbolizes celebrations on the part of angels, that heaven and the church had become the Lord's, as they had been from the beginning, and that they had now become those of His Divine humanity, thus that the Lord would reign over heaven and earth as regards both aspects of Him to eternity.

"There were loud voices in heaven" symbolizes celebrations on the part of angels. "Saying, 'The kingdoms of this world have become the kingdoms of our Lord and of His Christ,'" means, symbolically, that heaven and the church had become the Lord's, as they had been from the beginning, and now had become those of His Divine humanity. "And He shall reign forever and ever!" means, symbolically, that the Lord would reign over them as regards both aspects of Him.

Loud voices in heaven symbolize celebrations of the Lord for having now taken His great power, as is apparent from verse 17 following, where the substance of those great voices is presented.

The Lord here means the Lord from eternity, who is Jehovah, and the Christ here means His Divine humanity, which is the Son of God (Luke 1:32, 35).

[2] That the Lord will reign even as regards His Divine humanity is clearly apparent from the following passages:

The Father... has given all things into His (the Son's) hand. (John 3:35)

(The Father has) given (the Son) authority over all flesh... (John 17:2)

(Father,) all Mine are Yours, and Yours are Mine... (John 17:10)

All authority has been given to Me in heaven and on earth. (Matthew 28:18)

In reference to His Divine humanity the Lord also says that the Father and He are one, and that He is in the Father, and the Father in Him (John 10:30, 38; 14:5-12).

Furthermore, if the Lord's humanity is not acknowledged to be Divine, the church perishes, since the Lord cannot then be in man and man in the Lord, as He teaches in John 14:20; 15:4-6; 17:21, 23; and it is this conjunction that makes a person a person of the church, thus that makes the church a church.

[3] The Christ means the Lord's Divine humanity because the Christ is the Messiah, and the Messiah is the Son of God whose coming into the world was awaited by the Jews.

That the Christ is the Messiah is apparent from the following passages:

We have found the Messiah, which, if you translate it, is the Christ. (John 1:41)

The woman said to Him, "I know that Messiah is coming, who is called Christ." (John 4:25)

The reason is that Messiah in Hebrew means Anointed, as does Christ in Greek.

That the Messiah is the Son of God is apparent from the fact that the high priest asked Him whether He was "the Christ (i.e., the Messiah), the Son of God" (Matthew 26:63, Mark 14:61, cf. John 20:31). Also from the following:

...You are the Christ, the Son of God, who is to come into the world. (John 11:27)

(Peter said,) "We believe and acknowledge that You are the Christ, the Son of the living God." (John 6:69)

That the Lord is the Son of God in respect to His Divine humanity:

(The angel said to Mary,) "You will conceive in your womb and bring forth a Son... He will be great, and will be called the Son of the Highest... The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One who is to be born of you will be called the Son of God. (Luke 1:31-32, 35)

And so on in many places elsewhere.

It is apparent from this what is symbolically meant by the statement that the kingdoms have become the kingdoms of our Lord and of His Christ.