I'm having trouble picturing this. Do you have a picture? And what kind of alarm did you use?
Did the fence help/deter thieves?
Which alarms did you use (quite a few Doberman options) and how did you set them up?
I'm a Lutheran but not Catholic; I do have Catholic friends and family.
All visitors are welcome! Locked doors could be for safety in a bigger city; perhaps they've had break-ins and/or vandalism in the past or maybe no one was in the church at the time so last one out locked it.
I would suggest dressing in casual fancy or dressed up (jeans or fancy pants and a polo or dress shirt) since it is a special occasion (though some could argue that church is always a special occasion hence...