The Gospel is the binding of satan.
That's not what bible says:
Rev 20:1 And I saw an angel come down from heaven, having the key of the bottomless pit and
a great chain in his hand.
Rev 20:2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and
bound him a thousand years,
Rev 20:3 And
cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season.
What God uses to control satan:
1. Bound with a great chain.
2. cast into a bottomless pit.
3. Shut him up in that pit. Likely a reference to the lock the key goes to that the angel has.
4. A seal is also used on him.
Satan is much more than just "bound". The gospel is not mentioned one time regarding this binding and imprisonment.
Satan is bound by a chain which means to have it wrapped around him preventing arm and leg movement ie: incapable of moving. Whether the chain is spiritual or literal doesn't change what it's purpose and it's result. It's is irrelevant whether it's made of steel, gold, plasma or kryptonite.
He is also cast into a bottomless pit which is where the Genesis fallen angels are also kept. Satan is "shut up" in this pit which is a prison for angelic beings. He is also "sealed". So there are three things that bind and imprison Satan both physically and spiritually. Satan cannot leave the pit or influence anything outside of the pit nor in the pit. He is completely and utterly incapacitated. Any doctrine that teaches anything otherwise is changing what the scriptures present. When this happens, the world will be without Satan's deceptions and lies for the first time in history. This is the perfect time for the gospel to finally reach those who normally would be deceived and incapable of hearing or accepting the gospel. In addition these same people will be under the shepherding rule of Jesus and his resurrected priests and kings who are Christian saints, many having been murdered in the great tribulation. None of this has yet happened.
Any doctrine that teaches Satan will have any amount of influence and mobility and power outside of the pit, and can deceive anyone during the thousand years is teaching things that scripture does not teach and in fact contradicts what scripture does teach about Satan and that time period.
1Pe 5:8 Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour:
Eph 6:11 Put on the whole armour of God, that ye may be able to stand against the wiles of the devil.
Eph 6:12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
1Thess 2:18 Wherefore we would have come unto you, even I Paul, once and again; but Satan hindered us.
Further proof that Satan is not imprisoned but is free and has hindered even people as important as Paul. This supports Premill as the correct doctrine in regard to Satan not being bound and imprisoned in the pit at the cross or resurrection.
Amil: Satan is like a dog on a long chain that is able to move around his own territory, doing what he wants and deceiving people but is "limited" by the gospel.
Premil: Satan is bound by a chain (most likely this means to have the chain wrapped around him so he is disabled mobility wise) and then cast into a pit, and then a seal placed on the pit. A key is needed to open it, so it is also locked with that same key. This means Satan cannot deceive anyone in the slightest, this means complete control over Satan, and this means Satan cannot get out of the pit nor influence anyone else at all. Premill is the only doctrine that matches the language in Rev 20.