If you have a proper genealogy, then you already know what religion they were, since you have the records. However, names don't have religions. That is a common amateur mistake. There are too many Catholic Grossmanns and Jewish Schmidts for that to have any meaning whatsoever. All you can say without a doubt is that Weispfennig is Germanic.
Just a quickie look showed many Weispfennigs in Prussia, all of whom were christened, which eliminates any chance that those particular Weispfennigs were Jewish. The records go back to the 1700s.
And actually I don't have a company. I am an independent contractor. I work on a contingency basis with Just Answer. They provide the forum and I provide the research.
If you have concerns about the company, they do have an A+ rating with the BBB. You can contact***@******.*** with any financial questions. Those of us who answer the questions know nothing about the financial arrangements customers make with Just Answer.
I am still available if you would like me to try to determine what religion they were, but if you already have the genealogy, the question is moot.
Good luck with your research.