Pope Benedict XVI has reversed centuries of traditional Roman Catholic teaching on so-called limbo, approving a Vatican report released Friday that says there were "serious" grounds to hope that children who die without being baptized can go to heaven. Theologians said the move was highly significant - both for what it says about Benedict's willingness to buck a long-standing tenet of Catholic belief and for what it means theologically about the Church's views on heaven, hell and original sin - the sin that the faithful believe all children are born with.