god bless you (as some like to say), keep your religion private and you'll never get into trouble!

Oh by the way, nothing important but next time consider learning how to manage your budget.
There is a bus from down town Montreal to the airport.
Don’t really understand (and don’t care) where you got this tax charge as the Canadian customs don’t charge foreigners any tax, they even return the GST to foreigners, at the airport.
So you could have made a few extra dollars from at least the gift you bought your mother.

I sense a bit of naiveté or lack of life experience from your side, but maybe it’s just my impression.