If you were to suggest in a public forum that just possibly Israel's failure to reach a peace agreement with a terrorist organization run by kleptomaniacs and homicidal maniacs, which still continues to applaud the murder of Israeli children, might possibly be due to the terrorists and not because of Israel, then according to the consensus of the left, you are an Israel Firster.
The paradigm of the Israel Firster only works if you assume that the America First position is to support Islamic terrorists. Even if we were to dismiss the threat of Islamic terrorism to the United States then a position sympathetic to the territorial claims of Islamic terrorists in Israel would still not be the America First position. It would be the Muslims First position.
The left, which deploys names like Israel Firsters, is certainly not calling for neutrality in the conflict, rather it would like us to side with the Muslim Brotherhood and the assorted Islamic terrorists scattered throughout the region. Arguably the United States has been doing this for some time already.