I've been reading sections from the Ante-Nicene fathers lately, and seeing what they had to say about all things related to the end times near the second coming of Christ.
Here are just a few quotes I found very interesting. The following two quotes both show that Irenaeus & Hippolytus expected the antiChrist to be a Jew, and that he would specifically come from the tribe of Dan. More modern schools of thought think that the antiChrist will be from Italy or possibly an Arab.
"And Jeremiah does not merely point out his sudden coming, but he even indicates the tribe from which he shall come, where he says, “We shall hear the voice of his swift horses from Dan; the whole earth shall be moved by the voice of the neighing of his galloping horses: he shall also come and devour the earth, and the fulness thereof, the city also, and they that dwell therein.” This, too, is the reason that this tribe is not reckoned in the Apocalypse along with those which are saved." - Irenaeus
"Thus did the Scriptures preach before-time of this lion and lion’s whelp. And in like manner
also we find it written regarding Antichrist. For Moses speaks thus: “Dan is a lion’s whelp, and he shall leap from Bashan.” But that no one may err by supposing that this is said of the Saviour, let him attend carefully to the matter. “Dan,” he says, “is a lion’s whelp;” and in naming the tribe of Dan, he declared clearly the tribe from which Antichrist is destined to spring. For as Christ springs from the tribe of Judah, so Antichrist is to spring from the tribe of Dan. And that the case stands thus, we see also from the words of Jacob: “Let Dan be a serpent, lying upon the ground, biting the horse’s heel.” What, then, is meant by the serpent but Antichrist, that deceiver who is mentioned in Genesis, who deceived Eve and supplanted Adam (πτερνίσας, bruised Adam’s heel)? But since it is necessary to prove this assertion by sufficient testimony, we shall not shrink from the task.
That it is in reality out of the tribe of Dan, then, that that tyrant and king, that dread judge,
that son of the devil, is destined to spring and arise, the prophet testifies when he says, “Dan shall judge his people, as (he is) also one tribe in Israel.” But some one may say that this refers to Samson, who sprang from the tribe of Dan, and judged the people twenty years. Well, the prophecy had its partial fulfilment in Samson, but its complete fulfilment is reserved for Antichrist. For Jeremiah also speaks to this effect: “From Dan we are to hear the sound of the swiftness of his horses: the whole land trembled at the sound of the neighing, of the driving of his horses.” And another prophet says: “He shall gather together all his strength, from the east even to the west. They whom he calls, and they whom he calls not, shall go with him. He shall make the sea white with the sails of his ships, and the plain black with the shields of his armaments. And whosoever shall oppose him in war shall fall by the sword.” That these things, then, are said of no one else but that tyrant, and shameless one, and adversary of God, we shall show in what follows." - Hippolytus
Many opponents of pre-tribulation eschatology state that the "pre-trib" idea first came from a girl having a vision in the early 1800's, but to be fair, I think there's some obscure writings from centuries before that which could be viewed as supporting a pre-trib rapture. However, it is clear to me that in the first few centuries after Christ, a post-tribulation view was commonly and clearly accepted.
And therefore throughout all time, man, having been moulded at the beginning by the hands
of God, that is, of the Son and of the Spirit, is made after the image and likeness of God: the chaff, indeed, which is the apostasy, being cast away; but the wheat, that is, those who bring forth fruit to God in faith, being gathered into the barn. And for this cause tribulation is necessary for those who are saved, that having been after a manner broken up, and rendered fine, and sprinkled over by the patience of the Word of God, and set on fire [for purification], they may be fitted for the royal banquet. As a certain man of ours said, when he was condemned to the wild beasts because of his testimony with respect to God: “I am the wheat of Christ, and am ground by the teeth of the wild beasts, that I may be found the pure bread of God.” - Irenaeus
Another interesting idea I've come across is that Irenaeus (possibly others) were certain that the world would end after 6,000 years, followed by a 1,000 millennium "rest" period to reflect a 6-day week followed by a sabbath day of rest. If that's true, we're very close to the end depending on when one dates the beginning of creation.
For in as many days as this world was made, in so many thousand years shall it be concluded. And for this reason the Scripture says: Thus the heaven and the earth were finished, and all their adornment. And God brought to a conclusion upon the sixth day the works that He had made; and God rested upon the seventh day from all His works. This is an account of the things formerly created, as also it is a prophecy of what is to come. For the day of the Lord is as a thousand years; and in six days created things were completed: it is evident, therefore, that they will come to an end at the sixth thousand year. - Irenaeus