I brought this up in another thread. I think it's very important to keep Satan out of the context of God when considering his reach. He's not omnipresent or omniscient as is God. To say that Satan is everywhere implies a God attribute that should be reserved for God. Some may flippantly say "the devil" or "Satan", when they mean his army of evil spirits, but I don't think this should be said flippantly. It tends to put him on the level of God as an omnipresent spirit when he is just a created one. He was well aware of Jesus, but I'm not so sure he even knows I am around.
From 1 Peter, chapter one (and keep in mind, Satan was a created angel that fell):
" 10Concerning this salvation, the prophets, who spoke of the grace that was to come to you, searched intently and with the greatest care, 11trying to find out the time and circumstances to which the Spirit of Christ in them was pointing when he predicted the sufferings of Christ and the glories that would follow. 12It was revealed to them that they were not serving themselves but you, when they spoke of the things that have now been told you by those who have preached the gospel to you by the Holy Spirit sent from heaven. Even angels long to look into these things."
But I would never discount the war going on around us all the time. I know there is spiritual warfare going on over my soul. Obviously, I don't have a clear picture of Hell's corporate structure, but I believe there are evil spirits that are very aware where my weakness are and are trying to exploit them. It is only by calling on the Power of God that we can fight against this evil legion.
Ephesians 2:9 when Jesus is addressing an evil spirit:
9Then Jesus asked him, "What is your name?" "My name is Legion," he replied, "for we are many."
Ephesians 6:
"10Finally, be strong in the Lord and in his mighty power. 11Put on the full armor of God so that you can take your stand against the devil's schemes. 12For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms. 13Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. 14Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, 15and with your feet fitted with the readiness that comes from the gospel of peace. 16In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. 17Take the helmet of salvation and the sword of the Spirit, which is the word of God. 18And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the saints."
Good discussion, Faith!