Christian Reconstructionism is a subgroup of the radical
Christian Right. The biggest difference between
the Reconstructionists and the rest of the Christian Right is that
the Reconstructionists wish to enforce Old Testament civic laws.
However, the Reconstructionists don't wish to engage in some sort
of revolution to take over the world, but rather believe that they
can convert the world to their point of view through massive
proselytization. The large majority of the Christian Right
rejects these views, both because they are uncomfortable with the
idea of enforcing the Old Testament civic laws, and also because
of theological disagreements.
This difference comes about from how they interpret one quote from
Christ, and several different quotes from St. Paul; all quotes
here are from The Living Bible; Paraphrased, by Tyndale
House Publishers. In the first quote, Christ to his disciples,
Matthew 5:17-19
Don't misunderstand why I have come -- it isn't to cancel the laws
of Moses and the warnings of the prophets. No, I came
to fulfill them, and to make them all come true. With all the
earnestness I have I say: Every law in the Book will continue
until it's purpose i achieved. And so if anyone breaks the least
commandment, and teaches others to, he shall be the least in the
Kingdom of Heaven. But those who teach God's laws, and obey
them shall be great in the Kingdom of Heaven.
Examples of the quotes from Paul, which all boil down to the same
thing, Paul writing to gentile converts, are Galatians 3:2-3
Let me ask you this one question: Did you receive the Holy
Spirit by trying to keep the Jewish laws? Of course not, for
the Holy Spirit came upon you only after you heard about Christ
and trusted him to save you. Then have you gone completely crazy?
For if trying to obey the Jewish laws never gave you spiritual
life in the first place, why do you think that trying to obey them
now will make you stronger Christians?
and Galatians 3:24-25
Let me put it another way. The Jewish laws were our teacher and
guide until Christ came to give us right standing with God through
our faith. But now that Christ has come, we don't need those laws
any longer to lead us to Him.
Most Christians interpret this to mean that the Old Testament
laws were fulfilled with Christ's crucifixion and
resurrection, so that they no longer apply to humanity. However,
the Reconstructions hold that, since God is eternal and
unchanging, the morals (and laws) under which people should live
are unchanging, and thus the Old Testament laws are still valid.
They take the quote from Jesus to be a reaffirmation of those
laws, and that the quotes from Paul only apply to the ceremonial
laws, not the moral and civic laws.
Another theological difference between Reconstructionists and most
other conservative Christians is postmillenialism versus
premillenialism. Premillenialism, which most conservative
Christians hold to, is the belief that Christ will come after the
Apocalypse, in accordance with Revelations, and establish a
1,000 year rule on Earth. Postmillenialism, which
Reconstructionists believe, holds that Christ will only come after
the Earth has been turned into the Kingdom of God, by which they
mean all the governments of the world are run as
theocracies upholding the Old Testaments laws.
Postmillenialists do some fancy hand waving in order to claim
that the events in Revelations have already happened, to keep
their theology consistent.