If this has not been a huge issue in your family so she would know what you are talking about, you might try asking your mother what to do about a guy who is always trying to hug you when you don’t want to be hugged.
In this day and age, your mother should say who is trying to hug you when you don’t want to be hugged?!?!?!
Then you can answer, well, you know, Mom. The priest when we go to church.
If she sees it as a problem not connected to the church first, she might understand the problem better.
ETA: too many people have been raised to believe you have to be “respectful” in this way. It is not true that we have to be respectful when people are not being respectful of us, but we do not have the social niceties in place yet to deal with it, so refusing seems rude to people.