Can Christians be Possessed by Demons?

About a year ago I was studying angels and demons with my students at church. During our discussion/research, one of the topics was demon possession. I wondered to myself, "Can Christians be possessed by demons?" I found this an important question to answer because I've been a Christian since my youth and if demon-possession in Christians were possible, I'd want to know what I could do to prevent it. So, I checked out the Bible to see what it said, and here's what I found:

This is how you can recognize the Spirit of God: Every spirit that acknowledges that Jesus Christ has come in the flesh is from God, but every spirit that does not acknowledge Jesus is not from God. This is the spirit of the antichrist, which you have heard is coming and even now is already in the world. You, dear children, are from God and have overcome them, because the one who is in you is greater than the one who is in the world. --1 John 1:2-4

We know that anyone born of God does not continue to sin; the one [Jesus] who was born of God keeps him safe, and the evil one cannot harm him. We know that we are children of God, and that the whole world is under the control of the evil one. We know also that the Son of God has come and has given us understanding, so that we may know him who is true. And we are in him who is true—even in his Son Jesus Christ. He is the true God and eternal life.
--1 John 5:18-20

According to these verses in First John, God is greater than Satan, and those who are "in [God] Him" or "saved" are protected by Christ. Satan cannot touch those who will inherit salvation. Therefore, if Satan cannot touch practicing Christians, he cannot possess them himself. Nor can his demons possess practicing Christians because if Satan has no power against Christ, neither will demons, who are below Satan and submissive to him.

I say "practicing Christians" because there are many people in this world who claim to be "Christian" but they have nothing more to do with God than the fact that they believe He exists. Being a Christian is not simply belief in a higher being but it includes believing that Jesus came to die for our sins to give us a second chance, and accepting the fact that we cannot get to heaven on our own efforts. God's forgiveness is an act of grace, which is a gift we don't deserve. Once we have accepted this grace, we must then do our best to become like Christ and live a life obedient to God.

Those who believe in God by name only are not Christians, and they do not have God's protection against Satan and his schemes. However, those whose faith shows through in their lifestyle have clearly declared Jesus as Lord, and God protects them from Satan's schemes. It brings me peace to know God's got my back, and I hope you have the same peace.