No, it is not sinful to make purchases in secular bookstores. If you have a Catholic bookstore in your area, it would be good to support it by buying your Catholic materials there even if they are a bit more expensive than in a chain bookstore, but that doesn’t mean that you can’t go to secular bookstores. Just about every store you patronize – including Catholic bookstores, unfortunately – will have some products that do not entirely conform to the Catholic faith. It is your job as a consumer to use prudential judgment, but you need not boycott every store that provides anti-Catholic materials for purchase.
