Used correctly, no contraceptive in the world has a 100% success rate. (Unless you count abstinence, and the Church has no objection to that one.) The effectiveness of condoms used correctly is only 85%.
Even the Supreme Court in the Casey decision justified abortion by arguing that it was necessary as "backstop" contraception.
I don't think you're right on the effectiveness of perfect condom use. A Johns Hopkins publications puts it at 97%, with average use at 86%.
http://www.infoforhealth.org/pr/h9/h9chap4.shtml
Mrs VS
. (Unless you count abstinence, and the Church has no objection to that one.)Lesbianism is also 100% effective (although the Church opposes that).