The correct answer is the following.
Forming their own churches after the war was important to African Americans because during slavery they had to attend to their services in secrecy.
That is when blacks could express themselves in a free way in their churches and communities. Of course, they could better do so in the Northern states because, in the South, they still were living mane segregational situations. Freed African Americans founded their own churches that in one way or another allowed them to have a place of their own to pray, meet, and help each other.