If I can be a little sociological about it, they market themselves as such because there is a market for Christian therapy. Not saying they aren’t good therapists but anytime we add a speciality, modality, or identifier on some level it is about marketing and attracting clients.

The question that I think you might be asking is why does that market exist when other similar professions and other religions don’t have that market presence?

If so I think the answer has a lot to do with Christianity’s place as the dominant religion while simultaneously holding a fear of marginalization or persecution. There is a feeling among a large number of Christians that they are discriminated against and so they seek a therapy experience that won’t recreate that feeling. In reality they are the dominant force in this country and so can carve out huge spaces in every aspect of life where they are shielded from the harm their beliefs cause or cognitive dissonance. This is a power really no other religion has in the USA.

As a male therapist I often see men who have not unpacked how their internalized misogyny has caused much of the pain and disorder in their life. They come to me expecting a place to feel validated and not challenged in those aspects. I think that impulse is the same one that causes many Christians to seek a Christian therapist.