Well at its root, Christianity means a body that follows Christ. Therefore, there cannot be divisions within a body. Sin causes people to separate, but there is no division in Christ.

Christianity can be taught in Christian schools, but it is most commonly taught in building where the church (the body of believers) gathers to listen to a pastor.

liturgy - receiving communion (the Body and Blood of Christ)

As long as it takes the body to be resurrected.

A church denomination is an identifiable religious body operating under a common name, structure, and doctrine within the main body of Christianity.