When considering "great tribulation" not since the beginning of the world to that particular time, how can 70 AD qualify, since it did not destroy all but eight human souls as the world wide flood in the days of Noah had? How can it be said "as was not since the beginning of the world to this time" since history shows us the first temple and city were destroyed in similar manner as they were in 70 AD?
Matthew 24:21 (KJV) For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
We find evidence of "great tribulation" coming against the church because false prophesy that led away the servants of Christ was allowed to be taught in the church. This is doctrine originating from the depths of Satan and unless the church repents will bring "great tribulation" upon the church.
Revelation 2:21-29 (KJV) And I gave her space to repent of her fornication; and she repented not. Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds. And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works. But unto you I say, and unto the rest in Thyatira, as many as have not this doctrine, and which have not known the depths of Satan, as they speak; I will put upon you none other burden. But that which ye have already hold fast till I come. And he that overcometh, and keepeth my works unto the end, to him will I give power over the nations: And he shall rule them with a rod of iron; as the vessels of a potter shall they be broken to shivers: even as I received of my Father. And I will give him the morning star. He that hath an ear, let him hear what the Spirit saith unto the churches.
John was shown a vision of "all nations, kindreds, people and tongues" calling them a great innumerable multitude no man could number. The angel tells John "these are they which came out of great tribulation" having washed and been made white through the blood of the Lamb. This too suggests the second destruction of the city and temple in 70 AD does NOT fit.
Revelation 7:9-10 (KJV) After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands; And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
Revelation 7:13-15 (KJV) And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they? And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb. Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.
At the Olivet Discourse Christ, speaking to His disciples, (the first Jewish Christians of "great tribulation" they should expect, as well as all who follow after Christ through them) warns them that they and we will understand that as the Gospel of the Kingdom of God is proclaimed through Jesus Christ in this world, faithful CHRISTIANS should not be surprised by "great tribulation" that is certain to follow.