what are the important event in the church scene of to kill a mockingbird

Do you mean when the Finch Kids visit First Purchase Church (Calpurnia's church)?

I'm thinking that's what you mean. I suppose Lula gets angry that Calpurnia is bringing white children to a black church. The other parishioners talk her down and apologize to Scout and Jem. The kids also notice how humble the people are and how poor they are as well. Still there is such a strong sense of community and purpose.

The most important part of the children's experience in the black church is they way they see Calpurnia. In this scene they actually experience her intelligence...... they think she speaks differently among the people from her church, but she is in fact, acting like herself.