WASHINGTON — In breaking publicly with Roman Catholic bishops over the health care bill, a group of nuns has once again exposed the long-running rift between liberal and conservative theology in the Catholic Church.

The issue dividing them is whether the Senate version of the legislation goes far enough in limiting the use of federal subsidies paid for insurance policies that cover abortion. Progressive Catholics, including the group of more than 50 nuns representing thousands more from various religious orders, said this week that they would support the Senate bill. The traditionalists, like the United States Conference of Catholic Bishops, said they would oppose it.

Although both the nuns and the bishops firmly oppose abortion, they have reached different conclusions about the bill, a divide that is also playing out more broadly among other groups that oppose abortion.

These include Democrats in the Senate like Bob Casey of Pennsylvania who are comfortable with the restrictions in the Senate health care bill and Democrats in the House like Bart Stupak of Michigan who are fighting for tighter restrictions. That divide is proving central to the outcome of the health care debate — Mr. Stupak and his allies were continuing to fight Friday night — as Democratic leaders scrambled to come up with the votes to pass the legislation.