Religion tends to be the stronghold of reaction. And in that aspect, religion as an institution of control should be done away with. However, religion as an institution of worship should remain.

While the ultimate goal is freedom from religion, there also needs to be freedom of religion.

While I would recommend Marx's answer to the Jewish question as a reference text, Anna Louise Strong's "the first time in history" has a section regarding what the soviets did with religious institutions which is much more comprehensive.