Since you haven't mentioned any specific religion, therefore I will be explaining effects of computers in general or in the context of all kinds of religions. NO religion in the world stops anyone from using the computer. However in some religions, viewing the sites related to pornography or for using internet for doing crime, illegal activities such as hacking, stealing personal information from some one's computer etc are considered as immoral. The good effects related to computer are increase in knowledge, transfer of information from one individual to other, information sharing, increased links between the communities, discussions on blogs on different social issues etc. Therefore it depends upon the usage of computer which makes it moral and immoral in the context of any religion.
If computers are bad in a specific religion then the religion is bull because computers hadn't been invented when most (probably all) religions were formed