Reconstructionism begins from a definition rather than a doctrine. Mordecai Kaplan argued that Judaism is not a religion in the sense that Christianity is a religion, but an evolving religious civilization: a people with a history, a language, a literature, an art, a body of law, a land and a religion, of which the religion is one component and not the whole.
Two consequences follow, and they are what make Reconstructionism theologically the most radical and behaviourally among the more traditional of the American movements.
The first is about God. Kaplan rejected supernaturalism and reconceived God as the power in the universe that makes for salvation and for human fulfilment, not a person, not a lawgiver, not an agent who intervenes. Prayer is accordingly not petition.
The second is about law. If Judaism is a civilization rather than a revelation, then Jewish law is the accumulated custom of a people rather than the command of God, and the community has authority over it. Kaplan's formula is that tradition has a vote, not a veto. In practice Reconstructionist congregations retain a good deal of observance, because a civilization's customs are worth keeping, while feeling free to alter what they judge to be wrong.
The most conspicuous alteration is the rejection of chosenness. Kaplan removed the language of the chosen people from the liturgy, and the movement's 1986 platform states that the belief implies the superiority of the elect and the rejection of others, and is morally untenable.