When I had told my mother that I was going to observe Canon Law 1250, fasting on every Friday, she told me that’s ridiculous. Parents can be wrong in a lot of things, so it’s up to us to discern good advice from bad in light of God’s truth.
I think, for this particular topic, you should engage your mom’s argument with positive, IF she still wants to talk about it. I wouldn’t push the subject because whatever she thinks isn’t really going to affect you, but you will have a better argument for anyone else next time.
Think of what a church does for us. It’s a spiritual place of worship, a place where we attract all sorts of saints and sinners to worship God, to be in His presence, and to reflect on ourselves. It needs to be holy, quiet, accessible for a prayerful time, as well as convenient, clean, and beautiful because it needs to attract people there. Emphasize on the necessity of Catholic art, how it helps us reflect on scripture, on the saint, and makes us feel like they are alive with us as we celebrate Mass. The Crucifix and the Stations of the Cross around the building are necessary for us to reflect on the sacrifice of our Lord. We have to build a fitting place for our God to be in because He really is there in every church.
Look back at the Old Testament where God gave specific instructions on how to build the Ark, a beautiful golden masterpiece for God to be in, and then there’s the temple that Solomon built, approved by God with a pillar of fire. Then look at more recent events with our Mother in Guadalupe, in Lourdes. She wanted a church built there so that the faithful can congregate on that holy ground.
The church builds up the faithful, attracts them from all over the world, inspires them with art, and allows them to pray. Yes, there are churches or Mass centres that aren’t as great, but the beautiful churches are necessary to help the Catholic Church grow.
And here’s the kicker, when the Catholic Church grows, God can train virtue into every Catholic, and with those virtues, more Catholics will help the poor. That is what happened in the history of the Catholic church since the first century and up to now.