well,
drink wine and eat bread and say
"this is my body", do this in remembrance of me...
christianity is actually full of pagan influences, death/life stuff from egyptian, gnostic and mystic backgrounds
christmas and easter are extremely pagan, nothing to do with jesus but put in place by catholics to try and eradicate or replace the pagan traditions
almost nothing that christians celebrate is 'christian' but pagan or other
you could study this a bit and open up dialogue
you may have to bite your tongue a bit, but at least stress balance, fairness and equality of things
say "I will listen to you but you must also listen to me or we will respectfully just have to agree to disagree and honor each other's wishes