So what? Let's say I'm a Druid, and I want to sell gizmos and I know the people I'm trying to sell them to are Druids, and I go to them and say: "Hey, I'm a Druid, too!" in order curry their favor and further my sales.
So, what's wrong with that, morally - much less legally? What am I missing here?
If you find that Christianity is properly used by questionable characters, or even upright people, as a sales tool, you are not missing anything. Go for it.