Who says it is of the devil if people behave in a strange way. It is very dangerous to claim that something is of the Devil when it is not. This could be considered as blaspheming the Holy Spirit where there is no forgiveness. If you are unsure it is best not to say anything. It could be that the demons that control their lives are squirming when they feel the power of God, but I believe praying is still what God wants us to do more of.
Many verses support spiritual gifts such as, healing, tongues and the laying on of hands.
I drifted away from Pentecostal churches when I heard several people were leaving them and not being healed. There were disgruntled people who did not want to return to these churches and even believed everything they did was of the Devil. But this troubled me as I experienced Jesus in my experiences with them. The Bible says they are not necessarily Christians, as there are a group of people using or claiming to use the gifts. This verse may apply to most people in the Pentecostal churches.