I agree, if you banish and it comes back, it’s not a higher being like Lucifer that’s an Earthbound creature that doesn’t respect the rules and has free will, which is a rule on this planet. Lucifer respects free will ergo if you tell him to go away he will.
Ergo, impostor.
The thing you need to do here is after you have banished, set up wards. If your house is wide open anyone can walk in, so it’s like throwing a drunk uot the batr and not closing the doors - he comes right back for more… set up wards to fence out the time wasters and only allow in the invited.
We have techniques for this here:
Also you didn’t read @Ahmose link, get some more info before you assume anything at this point.