What happens to Non-Christians when they die? Death and Hell only have power over a fourth of mankind, according to Revelation 6. All others, straight to heaven. If the Green horse is supposed to be suggestive, then it would indicate at this point that Muslims go through that and not really anyone else. Comparing 1John with the Koran would make it abundantly clear why on the denial of the Father and Son. Seems to be the only unpardonable under grace that unquestionably subjects one to the Lake of Fire until the termination of the reign of the Son of God in 1Corinthians 15:24, 28.
If you're denying the Son, then you're obviously denying the place of Holy Spirit in the virgin birth, etc., etc. It's not a hard one to connect the dots on with how they regard the work of Holy Spirit as apostacy, as the Pharisees did in 1st Century Palestine. Even if the doctrine that some hold to were remotely valid about those under the power of death having had an extermination of consciousness until the resurrection, again that's only for the one-fourth of mankind that fit that sin 'cause 2Timothy 1 says that:
7 For God hath not given us a spirit of cowardice, but of power, and love, and correction. 8 Be not thou, therefore, put to shame - with regard to the witness of our Lord, nor with regard to me his prisoner; but suffer hardship together with the glad-message according to the power of God, - 9 Who hath saved us, and called us with a holy calling, not according to our works, but according to the peculiar purpose and favour - which was given to us in Christ Jesus before age-during times, 10 But hath now been made manifest through means of the forthshining of our Saviour Christ Jesus, - Who, indeed, hath abolished death, and hath thrown light upon life and incorruptibility, through means of the glad-message: (2Timothy 1:7-10 Rotherham's Emphasized Bible)
Elsewhere, obviously, Scripture says:
23 For, the wages of sin, is death; but, God's gift of favour, is life age-abiding, in Christ Jesus our Lord. (Romans 6:23 Rotherham's Emphasized Bible)
2Corinthians 5 indicates to me that to be absent from the body is to be present with the Lord is a part of the ministry of reconciliation, otherwise we'd be walking by sight and not by faith.
From a New Testament perspective, it's not a matter of what God will do to us for sin, but what we do to ourselves in the kind of resurrection into the body that we'll have for the New Earth, and perhaps in the ages to come after that when we're ultimately, finally made immortal. Some would quote Hebrews 9:27 that after death there's judgment, but the whole chapter must be factored into the interpretation of that verse where the High Priest of Israel was figuratively dead in his sacrifice for the people, and then the judgment of righteous for another year was rendered on the day of atonement in Old Testament Israel. So also Christ was offered once to bare the sins of many, but once and for all instead of annually, and He'll come again not to deal with sin but to bring salvation/deliverance/restoration according to what's the expectation of those that are waiting for Him -- is how the chapter closes.
Just don't wander into the falling away from the eonian life of God that's God's free gift, and it's all cool when you die. Book of Revelation only speaks death to Islam -- again, if the pus colored horse is supposed to signify that in Revelation 6, since they favor green in their flags and religious lighting more than anyone else on earth. It's not an unpardonable sin in this life, but unrepented of, it does seem to bind one to the second death in a peculiar way. And I would limit the expulsion of the dead from death and hades in Revelation 20 to that quarter of the world that Revelation 6 brings up since I'm a stickler for keeping things as much to the context of Scripture as possible.
However, you can make your future ages and your incarnation into the New Earth a very miserable existence if you give yourself over to disobedience to the Gospel of Christ with a sinful lifestyle. Romans 2 says that we receive in our souls, (i.e., into our mind, will, and emotions) for the things done in the body. That doesn't require an ethereal dungeon of what I like to fondly call mainstream dungeons and dragons Christianity.
Jesus comment in Matthew 7 about many coming in that day and I'll say I never knew you is explained by how your life will end with the following verses, as to whether or not you ever abode in the Word until you stimulated enough of the life of God to manifest within you into all of your circumstances and into your life, or if your whole body wasn't full of light and you wound up going down worse than the Titanic with all of the drama of this life that erroneously get called "acts of God" by insurance companies.