A lot of preachers warn believers against open doors to the demonic but the fact is that the vast, vast majority of demonized Christians were infested before salvation when every door and window was wide open. The demonic most often takes root during the formative (and mostly innocent) years of womb to mid-teens due to emotional /psychological trauma, whether real or perceived - I.e. imagined or planted by the enemy - and if not dealt with after salvation can linger without the afflicted being able to even fully comprehend where it came from in many cases.
Womb infestation can be caused by unwanted pregnancy, for example, which can be sensed by the unborn in the same way that playing certain music or singing to them can while in the womb. The unborn are sensitive to external stimuli including the mothers emotions, especially when voiced out loud. The resulting rejection detected by the unborn can have lasting effects even into adulthood if not dealt with post-salvation and in many cases the afflicted has no idea as to the root cause. Human memories of childhood only go back so far with clarity. Unexplained feelings of unworthiness, anger, resentment, etc can surface with little to no present stimulus. The person can be viewed as being ‘naturally disposed' to negative emotions as a result.
The message to open door messengers is that post true-salvation infestation usually only takes place due to willful rebellion. The presence of the demonic in believers is due to a time when ALL doors were open while living in a natural, sin state which every human being is born into. When dealing with demonized believers we should always look to life prior to salvation first, unless there are current overt signs of rebellion.
The issue is that the vast majority of church leaders have no understanding of the demonic, don’t know how to deal with casting the spirits out and either ignore or ostracize the afflicted. The title of ‘deliverance minister’ only exists because of this ignorance. Ignorance simply means that one isn’t informed - the negative aspects of ignorance come into play when it is by choice. Deliverance has become a specialty ministry when it was intended to be a part of ministry in general.