I was raised a theist. After high school I told my self that college would probably teach me a great many facts after which I could make an informed decision about religion. Working on a Ph.D requires ones total focus, so it was only after that that I could think deeply about religion. For some time I felt that religion was useful for two reasons: It provides a ready set of moral values, and 2) It provides a social group. Both of these are quite appealing.
Ultimately, I decided that a rational morality was possible independent of God. Also, I didn't need to socialize as much as in my youth. Religion lost its hold on me. My children thought religious meetings were stupid. (They are.)
In conclusion, religion served some purposes for me, but none survived the test of time. Religion served as early training in argumentation and critical thinking. However, all of the time I spent on religion could have been spent on better activities.