How can a Christian reject part of the Bible and still call themselves a Christian?

[Polaris]

I used to do that when I was a young adult. I recall arguing with a Messianic Jew about Leviticus 18.

I know am much more into following the Bible as it is written (I even abstain from blood though don't try the Kosher route because of a verse in Acts), but also understand that Christians are meant to judge within the community and let non-Christians be judged by God.

That means that even though homosexuality is a sin, it is not the responsibility for Christians to rule over the actions of those who are not Christians.

So yes, gay marriage is allowed when it is done by the state.