Thanks to St. Augustine with an assist from St. Paul, substitutionary atonement is more than an "alternative orthodoxy." It is a dogma of the Roman Catholic and Orthodox Churches, and one of the "fundamentals" of of Evangelical Protestantism. Chesterton thought that the doctrine of "original sin" was Christianity's great gift to the Pagan world, when in fact it was one of the ideas that increased the Christian tendency to bully and torture heretics and non-Christians. (It was considered better to die of torture designed to induce repentance than to die unsaved and go to hell -- or at least that is the best reading that can give to medieval practicers.)
Christianity, i think can be reformed and reinformed about Jesus' real message, but it would help if the church could "admit the exact nature" of its wrongs.