What is the ruling on viewing comments and posts of non-friends, both male and female, on Facebook, and does the ruling differ between the genders?

It is permissible to view people's pages and their comments on Facebook or other websites, because they are open and their owners permit viewing them. This is not considered spying, unless these pages contain something that is forbidden to view—such as forbidden images—or if there is a fear of corruption in religion and morals resulting from them, in which case viewing them becomes prohibited.