Why religions oppress women:

If you empower women, educate them, and give them control over their own birth rates, they (on average) have fewer children, allowing them to invest more in the kids they have - leading to better literacy rates. 1/4

Lower birth rates slow the spread of the religion (fewer babies to indoctrinate into the faith), and better education leads to higher de-conversion rates. 2/4

Higher levels of education also lead to increased economic success. While some studies have found that secularization tends to precede economic growth, wealthy countries are less likely to relapse back into religion (when you're less desperate, you're less vulnerable). 3/4

For the above reasons, religions that preach the subservience of women will naturally spread more successfully than religions that don't. 4/4

Note: This doesn't have to even be a conscious choice. It's not like a religion's founders thought through why they taught women should be ruled over or put that in the text to help it spread. It's just a feature that if a religion happens to have it, it's naturally selected for.