Part 1. No Heaven No Hell
Let's start with the biggest lie of all. The best trick the devil can pull on you, on any of us, is that he is not real and he's not interfering with your life. In fact he only has one job - to keep you from finding God. He only has one motivation, to be worshipped.
"Again, the devil taketh him up into an exceeding high mountain, and sheweth him all the kingdoms of the world, and the glory of them; And saith unto him, All these things will I give thee, if thou wilt fall down and worship me. Then saith Jesus unto him, Get thee hence, Satan: for it is written, Thou shalt worship the Lord thy God, and him only shalt thou serve." Matt 4, 8-10 KJV
From this passage we learn:
Satan has the ability to give of all the kingdoms of the world - this is how he rewards evil doing.
He desires to be worshipped above all.
The ability to resist the temptation of the devil comes from knowing the Word of God, knowing scripture.
So to the big question Why would a loving God allow the devil to torment us?
Simple biblical answer, He didn't. Man has the freedom to choose. Loving God would have no meaning if there was no other option, no other choice. But He set up the system whereby we have the absolute free choice to love God or to serve Evil. God sends no-one to hell, everyone freely chooses their own destiny.
I find the question "Why would a loving God allow the devil to torment us?" quite interesting. I am a fan of the movie "The Exorcism of Emily Rose" (2004) and in the final act of the film, the defence attorney (Laura Linney) asks the accused Father Moore the same question about Emily. And his answer is pretty much the same as you explain here.
Thanks for reading and your comment. I saw the film years ago. No one needs to remain under the oppression of evil, I just wish I had been less stubborn and found that out years ago!