Okay, firstly, false Christian is not the same as a demon in human form. Secondly, Christians do not need to live in fear and terror of the devil. It's true that he ( devil) always seeks to tempt real followers of Christ. He does that in every area of our lives though not just in our relationships with others. Are you afraid and paralyzed in every other aspect of your life? We shouldn't be cocky and think we are above being deceived or falling into temptation. However, we don't need to fear him and give his power more attention than we give Christ. That is what you are doing in all these posts. Honestly, I don't think you have any idea what you are supposed to be looking for in a potential spouse. If you really think that a demon or falsely converted person has no distinguishable characteristics than you are wrong. ( I can't believe I'm actually responding seriously to this thread again, haha)
We are guaranteed in Scripture that if we seek God and follow his will we will be blessed. We can avoid all these traps you are terrified of by regularly communing with God in prayer. Also, I'd like to add that as true Christians we have discernment ( from the Holy Spirit). We aren't going to wake up one morning and realize " oops, I married a demon" lol. Most of the time, when people end up in spiritually incompatible relationships it's because they ignored obvious red flags or settled for someone out of desperation.
The issue with sitting at home and waiting for God to bring your spouse to your door is that it is not practical. It's better to put yourself in situations to be able to meet new people and trust that God lead you to a suitable person.