Unitarianism proper was a non-Trinitarian denomination (or sect) of Christianity. Universalism was a denomination of Christianity that believed in the universal reconciliation of mankind to God. They dwindled and became more liberal, then united to form Unitarian Universalism, which shed its last vestiges of Christianity and became its own thing. Now it's a small quasi-religion that tries to access the truths of religion by aping its forms. They do little readings and light candles, and promote left wing politics. They don't have the cultus or drive to do anything as impressive as the People's Temple.