1 Timothy 3:16. And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory. This is dealing that Jesus Christ was God manifest in the flesh. (The Deity of Jesus Christ.) I John 4:1 Beloved, believe not every spirit, but prove the spirits, whether they are of God; because many false prophets are gone out into the world. 2 Hereby know ye the Spirit of God: every spirit that confesseth that Jesus Christ is come in the flesh is of God: 3 and every spirit that confesseth not Jesus is not of God: and this is the spirit of the antichrist, whereof ye have heard that it cometh; and now it is in the world already.

Jesus Christ was the God man.  John 1:14, Colossians 2:9

For in him dwelleth all the fulness of the Godhead bodily.

Colossians 1:26-28, v27  To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory: This mystery covers the fact that the Beleiver is now the temple of the living God 2 Corinthians 6:16

Ephesians 3:9 /5:30 For we are members of his body, of his flesh, and of his bones. 5:32 This is a great mystery: but I speak concerning Christ and the church. 1 Corinthians 12:13 For by one Spirit are we all baptised into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit.

There is only one Body of Christ inwhich each believer John 3:1-7  is a member of 1 Corinthians 1:27 . This is Body is also called the Bride of Christ which is one Body, Colossians 1:18 And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence.

This is a mystery which is knwon as the world wide curch, as their are many beleivers all over the world, and would be all caught up to meet the Lord in the air if Jesus returns in thier life time.

Romans 11:25 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. The fullness of the Gentiles are the kingdoms of this earth, which will end with the return of Jesus Christ to reign for a thousand years in Israel. Jerusalem will be trodden under foot until the thousand year reign of Christ. Luke 21:24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.

The Time of the Gentiles began when Jerusalem was destroyed by Nebuchadnezzar King of Babylon under the reign of Zedekiah King of Judah. The time of the Gentiles ends with the Literal return of Jesus Christ King of Kings and Lord of Lords.

1 Corinthians 15:51-52 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
1 Thessalonians 4:17
Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
The Church, The  Body of Christ known as The  Bride of Christ will not suffer the prophecy of Daniels 70th week “ Jacobs trouble” concerning Israel, known as the Great Tribulation 2 Thessalonians 2:7-11, Matthew 24:15  

2 Thessalonians 2:7 For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way. This mystery is dealing with the god of this world. 2 Corinthians 4:3-4. In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them. This mystery deals with the Anti Christ, deceiving Israel and sitting on the throne of David in the Temple that will be rebuilt in the midst of  Daniels seventieth week, which covers a seven years period. The Anti Christ is revealed in Revelatiion 6ff after  the churches gathering to meet the Lord in the air. Satan is the god Matthew 4ff, 1 Corinthians 4:4 this world and His time will be finished at the second advent where the premellinail reign of Christ will be for a thousand years . Jesus spoke of His return here in  Luke 21:24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled. The Roman Cahtolic church assists the Anti Christ and is not destroyed until Revelation 17:5, 18:2. The Devil knows he has a short time Revelation 12:12,  2 thessalonians 2:8 known as the pre – millennial  reign of Christ, when Jesus Christ takes the throne of David after Satans temple is destroyed. Acts 15:16 After these things I will return, And I will build again the tabernacle of David, which is fallen; And I will build again the ruins thereof, And I will set it up: Note: A good book on this subject is the ” two Babylons” written by Alexander Hyslop.

Revelation 17:1-5  And upon her forehead was a name written, Mystery, Babylon the Great, the Mother of harlots and abominations of the earth.

This is Satans false religion, or false church which is destroyed in the midst of the seven year Tribulation.