While you correctly point out that Gentiles should support Israel, that is not enough to be a righteous Gentile.
Maimonides gives the definition of a pious Gentile in Laws of Kings 8:11:
"Anyone who accepts upon himself the fulfillment of these seven mitzvot and is precise in their observance is considered one of 'the pious among the gentiles' and will merit a share in the world to come.
This applies only when he accepts them and fulfills them because the Holy One, blessed be He, commanded them in the Torah and informed us through Moses, our teacher, that Noah's descendants had been commanded to fulfill them previously."
A Gentile who follows non-Torah religions is not pious and has no share in the world to come, regardless of his support for Israel.