Many of the early Church Elders belived & taught about the Rapture. John The Apostle, Paul (Saul of Tarsus), Irenaeus, Cyprian, Ephraim The Syrian, Ignatius, Barnabas, and many others.
1 Thessalonians 4:15 through 5:4:
“For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep. For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air.
And thus we shall always be with the Lord. Therefore comfort one another with these words. But concerning the times and the seasons, brethren, you have no need that I should write to you. For you yourselves know perfectly that the day of the Lord so comes as a thief in the night. For when they say, “Peace and safety!” then sudden destruction comes upon them, as labor pains upon a pregnant woman. And they shall not escape. But you, brethren, are not in darkness, so that this Day should overtake you as a thief.”
As my immediately prior post notes, the debate is not (should not be) whether there is or is not a "rapture," but rather whether that event is chronologically distinct from the Second Coming.
The notion of a pre-trib Rapture is near completely non-existent among the post-Apostolic Church Fathers. The only fragment that some have used as support is one version (or two very different writings that exist with the same title) by the so-called "Pseudo-Ephraim." And even with that, there are elements that are very inconsistent with the dispensational framework into which the modern Pre-Tribulationistss cast the Rapture.
A few of the early Fathers (e.g., Irenaeus) give support to the notion of an earthly Millenium. But one searches in vain for any notion of a pre-tribulation rapture within their writings.