Christianity is not like Bitcoin, though. It does not need to maintain a single, uninterrupted chain (denomination) that everyone agrees with and is a member of.

It only needs to maintain consensus around one fundamental truth that all Christian denominations agree with and can therefore continue to call each other "brother" despite other differences of lesser importance that prevent them from maintaining organizational unity.

Namely the gospel of Jesus Christ as Savior and Lord to all those who have faith in him as the Son of God and in his atoning work on the cross for forgiveness of sin.

That's the only consensus I need to consider someone my brother in the faith, even if our other theological differences would prevent us from realistically worshipping together until Christ's return, when he will correct all of our errors and misinterpretations of his Word.