Read what Martin Luther says about debating with Satan when alone from volume 54 of Luther's works.
“Almost every night when I wake up the devil is there and wants to dispute with me. I have come to this conclusion: When the argument that the Christian is without the law and above the law doesn’t help, I instantly chase him away with a fart. The rogue wants to dispute about righteousness although he is himself a knave, for he kicked God out of heaven and crucified his Son. No man should be alone when he opposes Satan. The church and the ministry of the Word were instituted for this purpose, that hands may be joined together and one may help another. If the prayer of one doesn’t help, the prayer of another will” (LW 54:78).
Quotation from Luther’s Works is from the American Edition: vol. 54 © 1967 by Fortress Press. Used by permission. All rights reserved.