[Satan] knows he can’t improve, he can’t progress, that worlds without end he will never have a bright tomorrow. He is a miserable man bound by eternal limitations, and he wants you to be miserable too. Well, don’t fall for that.
Elder Jeffrey R. Holland, "Tomorrow the Lord Will Do Wonders among You", General Conference, April 2016
Satan is NOT stronger than us. He may have more experience so he knows what works, but he is not stronger than us. And, of course, he is not even close to the strength of God and His Christ.
It may seem otherwise when we are in the midst of being hit hard, but all we need to do is call for help.
I can't even fathom how miserable he is. Knowing he can't progress has to be so devastating. One third of Father's children are in the same boat. And we probably know some of them. How sad!
We still have an opportunity to progress and be better. That is exciting. That makes me so happy and relieved. But....if I don't try, then I'm in the same boat as Satan and his minions. Progressing requires two things; one is the Atonement of Jesus Christ, which was already done for me. And, two, is effort on my part to be better and work at it.
Sounds easy, but nothing worth having is easy. And eternal life with Heavenly Father is worth having.