What is the ruling on engaging in buying and selling with Christians for someone who suffers from obsessive-compulsive disorder and fears that this might lead to developing admiration for their religion?

It is permissible to engage in buying and selling with Christians and other disbelievers, except for things that are forbidden or that aid in forbidden acts. Muslims have unanimously agreed on its permissibility as long as what they possess is not explicitly forbidden. However, it is not permissible to sell weapons, war instruments, or anything that helps them establish their religion to people of war. Dealing with disbelievers in these matters does not contradict the rejection and hatred of their disbelief. As for obsessive thoughts (waswasa), they must be ignored.