I have non Jewish Co-Worker who often asks for a donation for her church, to the point where it makes me uncomfortable to say no. I see her every day. Is it permissible to give a small donation? Thank you.
No, it is forbidden to donate money to a Church. If this is causing animosity, perhaps you could buy her a coffee or some other nice gesture to maintain peaceful relations.
Shiltei Giborim,first chapter of Avoda Zara