Why does the NRSV translate Genesis 1:2 as 'a wind from God' instead of 'the Spirit of God'?

The problem starts with the Hebrew word ruach, which means both wind and spirit, just as the Greek pneuma does. So you cannot really condemn the translator who chooses "wind," if he thinks the context of water and movement supports it. And you should not translate a verse just to defend a theological idea like the Trinity; the decision has to come from the context and the etymology, not from a doctrine you want to impose. In this case, though, "spirit" does seem to fit, because the text has already put God into it, "in the beginning God created," and the special Hebrew word used means the Spirit is hovering over the waters, the way God is said to hover over his people like an eagle, which a mere wind does not do.