Someone asked me this question a long time ago. After all, Jesus says to pray for our enemies. The issue with praying for Satan, however, is that it will have absolutely no effect. Why? Because unlike us humans, his sin originated from within. Angels are pure spirits. Spirits differ from corporeal forms, such as ourselves, in that they don’t have a body. Our capacity for understanding is limited by our brain. (we have a spiritual capacity too as far as intellect goes, but we don’t get to use it unless we’ve become spiritual masters, for example, devout monks who achieve sainthood, or until we are dead.) Angels, on the other hand, had infinite theoretical knowledge of everything. They knew the law and the truth, and they knew exactly what would happen to them should they reject God. They were not tempted in any way shape or form. The concept of not being tempted into sin seems absolutely foreign to us. After all, there are probably none of us who knows what it feels like to not be at least tempted slightly by something. In fact, when I say I am not tempted, I really mean “the temptation is small enough to where I can unconsciously manage it.”
Before the fall, we could only be tempted externally, but after the fall we became able to be tempted from within, due to the fall corrupting our nature. When we fell, Satan tempted us externally. That means our flesh didn’t crave the sin like ours do. Yet, because of our minds, we saw the benefits of the sin and did not fully grasp the severity of the consequences. We knew we’d be punished, but we figured that the knowledge of good and evil was worth it. However, the understanding is that without the external temptation, we wouldn’t have even considered eating the fruit.
The demons, on the other hand, had no such external temptation. Nothing disordered came along to corrupt them. They became disordered on their own accord. The fact is, the demons, on their own accord, said that they would rather be banished into a lake of fire for all eternity than to willingly serve God. They knew exactly what they were doing and their actions would be irrevocable. Furthermore, they do not have a capacity for remorse. To this day, they are happy with their decision.
Lastly, God has already judged them and sentenced them to eternity in hell. We, however, have not been judged. We can still repent, no matter how evil we have been. We are incapable of committing an evil as pure as the demons. The worst we can do is reject God’s mercy at the end of our lives. Even if one of us was to sit here and wish God dead, that act would have originated from a sinful corruption. The very fact of the matter is that there is nothing that we can do, good or evil, that originates from ourselves. We cannot pride ourselves in any good we have done. Only through God do we perform good acts. But even then, we cannot even pride ourselves in our sins. For there is nothing that we can commit that would truly be original. It is all prompted through demonic influence, whether it be the concupiscence from the fall or from an external temptation. The extent of our action is to give consent. But even with that, it is still us doing it. We participate. We aren’t just robots who hand over the keys to God or Satan.