Is the rapture of the church a doctrine of demons? I am quite confused on the pre-tribulation, post-tribulation and no rapture.

I will try to give an adequate answer in a brief space. The word, rapture, means to be caught up. The doctrinal concept comes from the physical catching up of the saints to be with the Lord. As such, the rapture is a fact clearly taught in the Bible. 1 Thessalonians 4:17Then 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.
See All... states, "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." As you can see, we will be caught up. There is definitely a rapture.

With most Bible teachers, the disagreement comes with the timing of the rapture. (Though there are liberals who deny it altogether.) To explain this requires me to define some terms. First, there is the millennium. This is the doctrinal name for the thousand-year reign of Christ on the earth. Revelation 20:1-7 [1] And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand. [2] And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years, [3] And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season. [4] And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years. [5] But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection. [6] Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years. [7] And when the thousand years are expired, Satan shall be loosed out of his prison,
See All... mentions this thousand years six different times. Generally, people line up three ways on this event.

1. You have people who do not think the reign is literal. They are called amillennialists, which means "no millennium."
2. You have people who think that Jesus Christ will come at the close of the thousand years. They believe that the gospel of Christ will conquer the world and then Christ will come to His own. These people are called post-millenialists because Jesus comes after (post) the thousand-year reign.
3. There are those who believe that a thousand years of peace on earth requires the presence of Jesus Christ. These are pre-millennialists because they believe that Jesus will come before (pre) the thousand-year reign. I am a premillennialist because I believe it fits the Bible best.

Most premillennialists believe that the thousand-year reign will be preceded by a tribulation period of seven or, for some, three and a half years. They also believe that at some point Jesus will come for His own saints and take them up to be with Him before He comes down to the earth (as in 1 Thessalonians 4:13-18 [13] But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope. [14] For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him. [15] For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep. [16] For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: [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. [18] Wherefore comfort one another with these words.
See All...). However, I am losing count as to the different teachings on when Jesus will come. It seems to get more complicated each year. I will list the views I have heard the most.

1. Some believe that Jesus will come at the end of the tribulation and immediately come back down with the saints for His kingdom reign. These people believe in the post-tribulation rapture.
2. Others believe that Jesus will come in the middle of the tribulation. This is called mid-tribulation rapture.
3. Still others are teaching what they call pre-wrath rapture. As I understand this, it may not be exactly in the middle of the tribulation but it comes before God actually pours His wrath out on the earth.
4. Though its proponents may be splintering some, the most common teaching is pre-tribulation rapture. This means that Jesus comes at the beginning of the tribulation. This is my position. I believe that the New Testament strongly teaches that Jesus could have come at any time since the ascension of Christ. I do not see this as being possible unless He comes before the events of the tribulation as described in Revelation. I also see a strong New Testament emphasis on looking for the Son. Yet, I observe that those who teach other positions often get carried away in looking for signs. There are other reasons for my belief, but this gives you the idea.

The way people get carried away with arguing for their position and attacking all others, I can see how you might think that this is a doctrine of devils. However, it is just people trying to understand Bible prophecy. And, since we are all human, this opens up the door for human error. However, I can assure you that it is not a doctrine of devils.