Hello. First let me thank you for you ministry. My question concerns the authenticity of "slaying in the Spirit." I was once present at a service where this occurred. The name of Jesus was boldly preached at this service. A pastor I have great respect as a man of God for invited us to the service. However, my own pastor, who I also have great respect for, does not believe in this practice because it is not Biblical. I agree that it is not mentioned in the Bible. What would God's purpose be for this if it is genuine? If it's not genuine is it even safe? Does it open you mind for demonic purposes? Thank you for your time.
We also have a problem with the "slain in the Spirit" practice. First, it's not Biblical, as you pointed out, and second, the person who experiences this loses control. The fruit of the spirit (Gal. 5:23) is self-control, not loss of control, and why would God do that? 1 Cor. 14:26-39 addresses the importance of worship being orderly, not disorderly. And verse 32 says, "The spirits of prophets are subject to the control of prophets." So even those experiencing the leading and filling of the Holy Spirit in prophesying exercise self-control. That would be the principle, I would think, to govern a practice such as being slain in the Spirit, which appears to be a modern-day invention of man compared to the timeline of church history.
I believe it is a work of the flesh (like a lot--but not all--of speaking in tongues, in my opinion), and is a deception of either the flesh or of the enemy. I don't know if it opens one up to demonic purposes; many of those who experience it only want to pursue God. I wish I had a more definitive answer for you.