You don't say why you want to contact a church or where the church is located, so it's difficult to be specific.

If you are asking for help with family research, keep in mind that the task is not a priority for most churches and many churches don't have the personnel or the time to perform any type of research. You could write a very polite letter detailing exactly what information you're seeking and include a donation to the church and a self-addressed, stamped envelope.

Good luck!