Should I be nice or be a dick about the catholic church? Hmmm....
I'll be nice. Must...be...nice...
Try speaking with the clergy in the church you attend about how best to go about it. You could always try and start with managing investments/income with your local church. Once you've helped your church profit, you can always use that as a resume-builder to solicit additional responsibility.
Also, you can go round-about and solicit managing the investments of laypersons in the church who have influence. Once you help them make money, you can ask them to exert influence on the clergy to allow you to manage the local/ state church's funds. Or, you could name dropwhen you solicit your services to the clergy. An example would be to solicit yourself to a clergyman who has close links with one of your clients, as in, "I helped Joe Blow and his family realize an 18% annual increase in their portfolio in each of the last X years."
Or, once you have demonstrated an ability to the influential layperson that you can provide good investment advice, ask them to pass along your name to the clergy so yo can help the church enrich itself further.
Also, involve yourself in organizations such as the Catholic Foundation, or whatever else is available locally and use that as a way to increase your contact and solicitations with clergy and influential laypersons.
Good luck!