I was always under impression regarding Catholicism that all one has to do is follow the moral dictates of the church, say your rosaries etc. However, as Arthur Borges points out in a discussion group
"Not so simple! In Catholicism, I was merely taught a difference between "mortal" and "venial sins". Any number of venial sins on your soul at the time of death is said to send you to purgatory where they are roasted out of you, after which heaven throws open its doors to you. However one mortal sin is enough to send you to the eternal roaster deep down under. The whole trick for the clever sinner is to go to confession once a week to cut down exposure to the two netherworlds. If you really want to shave things close, you could even, say, premeditate your murder for late Friday afternoon, knowing that confessions start at 5 pm. However, with any luck in Catholicism, you will be given the sacrament of Extreme Unction when you are in agony (and hopefully to comatose to even think up something lusty), whereby the priest comes along and washes out everything. As an aside, the police here in France start most investigations by a visit to the priest who hears all these confessions. But of course he obeys his vow of absolute secrecy concerning everything said in the confessional..."