Should Christians in sales engage fellow churchgoers as prospects?
Not on Sunday morning, with the possible exception of an answer to the “what do you do” question that doesn't go too far.
But other than that…
It depends. Do you believe the thing you're selling is helpful, valuable, and can make people's lives better?
Or are you selling something because you need a paycheck?
If you truly believe what you're selling will make your fellow churchgoers better off, then you can make the argument it is wrong not to engage them.
It's sort of like the gospel, right? If you know someone that needs to hear it, you have an opening to share it, and you withhold it… you've negligently neglected a win-win-win opportunity.
If you are a fellow churchgoer of mine or if you and I are in community together, I will likely try to make your life better by making sure you know what I do and how I can serve you.
It's one of the ways I love my neighbor.