ROME, May 1 — Even at the Vatican, not all sacred beliefs are absolute: Thou shalt not kill, but war can be just. Now, behind the quiet walls, a clash is shaping up involving two poles of near certainty: the church's long-held ban on condoms and its advocacy of human life.

The issue is AIDS. Church officials recently confirmed that Pope Benedict XVI had requested a report on whether it might be acceptable for Catholics to use condoms in one narrow circumstance: to protect life inside a marriage when one partner is infected with H.I.V. or is sick with AIDS.

Whatever the pope decides, church officials and other experts broadly agree that it is remarkable that so delicate an issue is being taken up. But they also agree that such an inquiry is logical, and particularly significant from this pope, who was Pope John Paul II's strict enforcer of church doctrine.

"In some ways, maybe he has got the greatest capacity to do it because there is no doubt about his orthodoxy," said the Rev. Jon Fuller, a Jesuit physician who runs an AIDS clinic at the Boston Medical Center.