What's a door used for? Doors are used for select people to go through and keep others out. If there was no need to keep others out, there would be no need for the door, you could just leave a hole in the wall. Let's look at some doors:
Matt 25 And while they went away to buy, the bridegroom came; and they that were ready went in with him to the marriage feast: and the door was shut. 11 Afterward came also the other virgins, saying, Lord, Lord, open to us. 12 But he answered and said, Verily I say unto you, I know you not. 13 Watch therefore, for ye know not the day nor the hour.
Rev 4 After these things I saw, and behold, a door opened in heaven, and the first voice that I heard, a voice as of a trumpet speaking with me, one saying, Come up hither, and I will show thee the things which must come to pass hereafter. 2 Straightway I was in the Spirit:
Rev 3:8 I know thy works: behold, I have set before thee an open door, and no man can shut it: for thou hast a little strength, and hast kept my word, and hast not denied my name. Rev 3:10 Because you have kept my word of patient endurance, I will keep you from the hour of trial which is coming on the whole world, to try those who dwell upon the earth.
Isa 26:19 Thy dead men shall live, together with my dead body shall they arise. Awake and sing, ye that dwell in dust: for thy dew is as the dew of herbs, and the earth shall cast out the dead. Isa 26:20 Come, my people, enter thou into thy chambers, and shut thy doors about thee: hide thyself as it were for a little moment, until the indignation be overpast. Isa 26:21 For, behold, the LORD cometh out of his place to punish the inhabitants of the earth for their iniquity: the earth also shall disclose her blood, and shall no more cover her slain.
As we approach the tribulation hour, we understand that we have an escape, through a door that will open, then be shut. The purpose of the tribulation is: (see above) to punish the inhabitants of the earth for their iniquity: the earth also shall disclose her blood, and shall no more cover her slain. It is the time of JACOB's TROUBLE. So...what's the point? The point is, time is short, there is an escape available to you, but you have to be watching, and you have to be ready (Matt 25). I have seen evidence of the Lord delaying the events in this world from progressing too quickly. The world is about to turn upside down. The Lords power is the ONLY THING keeping this world from total chaos right now. He is patient, but remember, some day soon, the restrainer will be taken out of the way and all hell will break loose on earth. It's going to be so bad in fact, that many people's hearts will fail them in FEAR of what's happening to the world. Compared to how bad it will be soon, today's world (as screwed up as it is) will look like a picture of tranquility. Fearful times are coming. I say this not to scare you, but to encourage you to BE WATCHING, BE READY. A door in heaven is about to open, when it does, you want to be going through it. When is all this going to happen? I DONT KNOW. Soon. grace and peace