Why can't Christians say that parts of the Old Testament don't apply??..

[DeistPaladin]

This is the argument that Christians use, when Atheists ask why people don't stone their neighbors for working on the Sabbath, and things like that. How do you counter arguments that these rules were for an earlier time? I mean, there are some old testament verses about people's animals falling into pits that certainly don't apply anymore.

According to Christian theology, Jesus "fulfilled" the need to keep OT laws with his sacrifice on the cross.

During the early centuries of the development of the Christian religion, there were a wild variety of opinions about the OT. At one extreme were the Ebionite Christians who felt that the only thing Jesus changed was the need for animal sacrifice. All OT laws were still in force and salvation depended on one's ability to keep them. Historian and Bible scholar Bart Ehrman has written that their version of the teachings of Jesus were similar to what we find in the Gospel of Matthew. Essentially, the Ebionites were the most Jewish of the early Christians.

At the other extreme were the Marcionite Christians who rejected the OT, the Jewish god as a lesser, baser god and all things Jewish. Jesus was a higher god, separate from the Jewish god, Yahweh. Their scripture relied heavily on the teachings of Paul who clearly felt the old laws had no value in salvation.

Today's Christianity is like a patchwork of all these old versions and seems like a strange compromise between them. They've kept the OT but feel it no longer applies. They've kept the Jewish god but came up with this idea of the Trinity to merge Jesus and the Holy Spirit into the mix.