This is something what happened with me, too (but not exactly with Lucifer - you can read about this here; it wasn’t just a simple “wrong thoughtform” about Him).
The reason why you created automatically thought forms of a Deity without knowing Him/Her is inside you, and basically in human nature.
There are several ways you can overcome it.
- The more time you spend with a Deity, your trust in Him/Her will grows; you have to put your focus io the Deity, and your experiences with Him. You’ll realize fast (or before or after) that your experiences are always will defeat other’s, because this is yours (and this is the main reason why other people usually won’t handle your experiences well, will questioning you and fucking around you - because the lack of those kind of experiences like yours - this is the other side of the same horse).
- Lucifer (and some other Deities as well) usually told me that I have to trust in my senses. This is a very-very important thing here for several reasons. Trusting in your senses also means overcoming your inferior, mortal thoughts and “intellect”, which also causes this problem what we’re talking about actually.
Of course this isn’t an easy thing, because even when a conjurer thinks he trusted in his senses, in real he did things as his intellect demanded. With daily meditation, you’ll be able to leave behind it and problems connected to it as well.
Every time when I was about to work with a Deity after I’ve heard His call, I’ve started reading about Them. Of course, this means that no matter what you read, you’ll see a picture about the actual One. So what I did is nothing more than, I simply “forget” about what I’ve read, and let the Deity lead me, and I let myself to discover His very Soul.
The most hardest but effective way: ignore it.
It will be hard especially because your intellect want to know things, and want to know everything better, it doesn’t trust in senses, it leads itself wherever it want to go.
An another useful option in this case is, when you realize that you are started building false images about Them, because in this case you are already noticed that there is a problem - while lot of magickians in the same situation are not.