I saw the following meme on Facebook
The following was my response (with possible future typo corrections and additions):
1. It must be remembered that Satan sinned against greater light (i.e. knowledge) than all human beings, and probably than all other angels. He was probably one of the chief angels of God (if not THE chief; cf. Isa. 14 & Ezek. 28). He's the most guilty of all both in terms of greater light and in terms of being the greatest instigator of sin in others via temptation and lies down through the centuries. Satan probably led the angels in their falling away just as he instigated the Fall of Adam and Eve. Satan might also be the most gifted, powerful and intelligent of all creatures ever created (with the likely exception of resurrected and glorified human beings). So, Satan also sinned with greater accountability because of his superior intellect and powers.
2. It must also be remembered that grace (i.e. unmerited favor) and mercy are, by definition, not obligated. God didn't have to provide salvation for fallen creatures (whether human or angels). God would be righteous and just in never having provided salvation for either humans or angels.
3. Historic Christianity affirms God's exhaustive foreknowledge of the Future (whether Catholic, Eastern Orthodox, Arminian, Lutheran, Molinist, Calvinist etc.). The Bible predicts and prophesies that the devil will not repent and has been destined for ultimate and final judgment (cf. Matt. 25:41; Rev. 20:10; Gen. 3:14-15; Rom. 16:20). To pray for the devil's salvation would contradict God's revelation of the future and is therefore sinful because you're denying God's foreknowledge (and if a high view of predestination is true, like in Calvinism, then also denying God's foreordination).
4. For Protestants Christ died to redeem human beings. In the context of redemption and atonement the author of Hebrews states in Heb. 2:16, " For surely it is ***NOT ANGELS*** that he helps, but he helps the offspring of Abraham." There's no indication of Christ dying for angels. Yes, there's a sense in which Christ's redemption has a universal effect on all creation and so in that sense Christ redeemed it by His death on the cross. But in terms of penal substitution, Jesus only died for human beings. Additionally, Calvinists generally believe Jesus only died for the elect. I'm a Calvinist and I lean toward the Calvinistic doctrine of Limited Atonement, but I'm not dogmatic on it. I still think it could be false.
5. For Protestants, we interpret the Bible to teach that sinners (whether human or angelic) by nature cannot freely come to God in repentance and faith. That's because sinners are in bondage to sin (contrary to Pelagianism). It takes God's initiating/enabling grace to touch a person for them to be delivered from bondage to sin and to be able to now freely come to God (contrary to Semi-Pelagianism which says that sometimes man can self-initiate an application of grace). Catholics and Arminians are among those who believe this. If Calvinism is true, then God's grace is not merely initiating and enabling, but it's also sufficient and efficacious. Either way, God's grace is revealed in Christ's atonement, and that atonement also graciously makes possible the redemption of sinners. But as has been noted in #4 Christ died for humans and (in all probability) not for fallen angels.
