To complete my thought about Catholics and the Democratic Party: Catholics are generally far less pro-business than Protestants. (Recall the "Protestant Ethic" as giving rise to capitalism.) So educated Catholics gravitate towards the professions or to government employment, and uneducated Catholics (in the old days) to unions. Catholics are less individualistic than Protestants and are more likely to support social "safety net" programs. For all these, and other, reasons, the pro-abortion stance of the Dems has failed to radically alienate a majority of Catholics.
The differences between Catholic conservatives and Protestant conservatives, politically at least, are lessening at a great rate.
This view might have more validity 30 years ago. It really doesn't now. President Bush has garnered a majority of Catholic votes in 2004. Our Jewish elder brethren are just a few steps behind.