Is masturbating okay to do when religious but have needs?

Of course: Everybody enjoys their body. It lets you stay focused on other things, may even be necessary for you to study and get to sleep, lets you save the best for real love, and prepares you for adult life. Some religionists will try to frighten you about this. Those folks aren't your friends. Ignore them. None of the mainstream scriptures proscribe the practice, and it's doing nobody any harm.