There is no moral obligation for a Christian to support the state of Israel just because of their ties to Abraham, especially if the government is doing something wrong. In general, however, my perception of the nation is that its values are closely aligned to Christian values, so I tend to favor the things they do. I think I would have an easier time living in Israel than in Iran, for example. Iran sponsors terrorism and stirs up trouble in the region, whereas Israel primarily fights to maintain their existence among so many who want to wipe them out.