This is a great question. Here are some points to get you started.
- As far as we can tell, religion is as old as humanity and women have played an important role from the beginning.
- Unfortunately, when you go back in time, there is less and less evidence. However, through inscriptions and bits of information in literature, we can tell that women played an important role. For example, Celia Schultz's book on women in Roman religion is very good. She argues that women and female divinities played roles that were more than the typical female roles such as childbearing.
- When it comes to Christianity and Judaism, all you need to do is look up the various roles that women played in the Bible and you will quickly see that women were essential in all areas. For example, there were judges like Deborah, missionaries who even helped Paul like Priscilla, and people like Phoebe, who was even Paul's patroness! In addition, women were the first ones at the cross.
All of these points show that women played very important roles in religion.