Can you pay membership to the YMCA? Make purchases at the Salvation Army store?
According to the Mishna on today’s daf, if there is a garden or bathhouse attached to the ground of avoda zara, one is permitted to benefit from them she-lo be-tova – if he does not have to pay for that benefit – be-tova, however, that is, if he has to pay for it, then it would be forbidden. In the Gemara, Abaye explains that that be-tova and she-lo be-tova refer to tovat komarim – whether the money will go to pay the idolatrous priests. If the money simply will go to people who are worshippers, then it is of no concern to us.
Translating she-lo be-tova as making use of it without payment follows Rashi’s approach to the Mishna. According to Rashi, the Mishna is teaching that even though the payment that is being made will go to the priests and not to the actual avoda zara, nevertheless it is forbidden to give money that will benefit the idolatrous priests.
Although this approach is found in the Talmud Yerushalmi, as well, nevertheless Tosafot offers an alternative approach to the Mishna. According to Rabbeinu Tam, the question is whether the person who benefits from use of the garden or the bathhouse will owe a favor to the priests and to the avoda zara. If he will not owe them anything like that, then we view it as taking advantage of something that is ownerless, and it is permitted. The Ra’avad adds that owing a favor to the priests may lead to some level of social intercourse that may offer an opportunity for the priests to influence the person religiously.
According to this approach, there would be no problem if payment is made, since we do not perceive him as benefitting from avoda zara, since he has paid in full for the privileges that he is given.