i was baptised christian.
it's just a little water. (and i was a child so i couldn't really say "no, thank you")
but even then...it's a little water.
it's not islamism, where you have to go on without ham for the rest of your life, or have to cover your women up, or have to live with the fear of being considered a terrorist.
it's not judaism where you have to pass saturdays doing little, or have to go to religious events depending on costumes and traditions.
good thing about christianity? they teach to show the other cheek. and they teach to be nice to others.
which means that, unless anything major happens, just go for the "little water" and then stop altogether doing anything more. and if your mother insists, just tell her she's a bad christian for obligeing you to do more.
you had your "little water" it doesn't matter if you grow old or die or anything, for christianity, your ticket to heaven is already there...just as long as you keep to being a goody-two-shoes. (not even in the really strict term of it, just, you know, do confess your crimes before dieing)
that's all. and it's not even blasphemous. you need god? chit chat alone to an invisible ever-listening presence and be happy with it. (which sounds much like a madmens rantling, but hey, that's my way of praying to god, who are the others to tell me something? at least my god doesn't order me to kill infidels, or to obey laws made thousands of years ago, or something else. i respect other religions, as long as they respect my freedom to express my opinion)
she's christian, if she were to blackmail you into submission to christianity, she'd fail at her being a christian. she can speak to you, encourage you maybe, but she can't force your hand.
or just go and speak to the christian priest about it.
and 10% to tithes!? is she out of her mind!? i'm an italian speaking here, i'm (i suppose) closer to the pope than you are, so, i can assure you, tithes!? for the love of heavens, one euro is more than enough. (one dollar and fourty cents? reduce to maybe half a dollar) it's the thought that counts. and we already pay the christians out in the world ourselves with "8 per mille" here in italy...so...don't worry, my taxes will pay also for your mothers share.
*goes back to rambling about how he wish he had had the idea to found a religion on dragon gods*