The process of purchasing a vacant church is the same as that of investing in commercial real estate, typically. You will want to contact the owners of the building or the broker selling the building to get a tour of the building and more details.
Commercial real estate sales typically involve a great deal of communication between buyer and seller. You will want to get a tour of the building, learn the seller's desired price and any conditions they might have, as well as request copies of the blueprints and historical data on the building. You will want to negotiate your own price and conditions.
Once you have a fair idea of what the usable square footage and history of the building is, you will want to tour the neighborhood as well to ensure that there aren't any upcoming developments that might negatively impact the value of your purchase. You can also visit your city or county's zoning and land use office if you have specific questions about the property.
You might also consider working with a commercial real estate broker who can connect you with contractors and building inspectors to ensure that the property does not require any serious overhaul, as you could be required to pay for any improvements not up to the land use code. They can also help with price negotiations, although you do need to carefully weigh their advice as they do get paid to sell real estate.
Finally, you'll want to secure financing. You will need to work with a mortgage broker for this and typically will need to put down at least 30 percent of the cost as a down payment to secure financing.