Matthew 12:22-37 is the text that I used for Children's Church today. That's right, children. Three girls ages 7 and 8. And on Pentecost. Please read the text because I'm not going to quote it.
This is the text where Jesus heals a man with a demon, and then the Pharisees try to say he did that by the power of Satan or Beelzebub. First I had them define a demon. A demon is an angel who decided that he hated God and followed Satan in his fall. Beelzebub, of course, is just another word for Satan who was also an angel one. Jesus had healed a man by the power of the Holy Spirit, and the Pharisees credited the miracle to Satan.
It was at this point that Jesus declared that blasphemy against the Holy Spirit is the only unforgivable sin. Blasphemy can be defined as saying anything about God that is not true and attributing evil to him. Have you ever worried about blaspheming the Holy Spirit? If so, then you have not committed this sin. Some commentaries say that you cannot commit this sin today. I disagree, but God's unelect who die without accepting Christ will be unforgiven because they resisted him their whole lives.
Some examples of how people come close to blaspheming the Spirit: there was a blog where someone used Biblical evidence to prove that people cannot be perfect before going to heaven. A commenter said that the blog was Satanic. This blogger used much research to honor God and what the Word actually says, and a commenter carelessly attributed such honesty to Satan. I don't know if the commenter committed the unforgivable sin or not, but he or she did come close. If so, then that person has no remorse over it and will always think himself right.
I think another way to blaspheme Christ, if not the Holy Spirit, is to go green. Environmentalism is a very pagan religion. Jesus already saved the planet. We don't have to do it for him. In fact he is building a new earth for all people to live on. And when he comes back, there will still be a planet. We don't need to worry about greenhouse gases and carbon footprints. In fact, people who go crazy over the environment not only have no faith in God's salvation, they hate people. They want less children to be born, babies to be aborted, but you will never be able to tell them that they are wrong.
At this point, I compare and contrast the Holy Spirit with an evil spirit. The Holy Spirit is God himself. Only Christians have access to the Holy Spirit. Evil spirits are not equal to God as they are only evil angels. They try to get into all people's lives. You can let them in, but you cannot get rid of them by yourself.
In verses 43-45, Jesus explains how a demon will leave a person, that person gets cleaned up, but then he leaves the house empty, so the spirit comes back with 7 friends and makes that person worse than before. The problem here is he left the house empty. He moralized his life on the outside, but he never invited a replacement for the filth that was cleaned out. Only one person can keep a person clean on the inside, and that is Jesus, therefore you have to pray every day for the Holy Spirit's direction. He'll even remind you to pray.
Finally, Ephesians 6 says to put on the whole armor of God. Not your armor, God's armor. Not some of the armor, but all of it. Really, it boils down to constantly reading the Bible and praying each day. God will lead you to what is right and do the rest for you.