The church can not endorse the use of condoms to prevent STDs because it would be a lie for them to do so. Condoms do not prevent the incidence of STDs, only behavior modification will.
The first case of HIV was reported in both the Philippines and Thailand in 1984, and by 1987, Thailand had 112 cases of AIDS, and the Philippines had 135 cases. Thailand enacted a “100% Condom Use Program” in 1991. All brothels were required to have supplies of condoms, and condom vending machines were installed in all supermarkets, bars, restaurants, and other public gathering places. The program was widely accepted and implemented by the people of Thailand. Two years later the Philippines, working with the Catholic Bishops Conference of the Philippines (CBCP) established the program AIDS-free Philippines, which did not allow for condom use. By 2003, the infection rate in the two countries were as follows:
Adults and children with HIV
Thailand 570,000 Philippines 9,000
AIDS deaths
Thailand 58,000 Philippines 500
Population
Thailand 62,833,000 Philippines 79,999,000
HIV Infection Rates Per Million
Thailand 9,072 Philippines 113
Far more lives were saved in the Philippines through behavior modification in keeping with the standards of the Catholic church than were saved with the promotion of condoms in Thailand. Condom use encourages behavior that leads to STD infections, that’s the bottom line. Telling people to use condoms in lieu of stopping risky behaviors is like letting children play on railroad tracks. Sooner or later, they’re gonna get hit by a train.
Compare the Philippine infection rate of 113 per million to the US infection rate (as of 2006) of 3,900 per million. For all our hundreds of thousands of condoms and all our wonderful medical technology, the Philippines is containing the spread of the disease far better than we are.
The effectivity rates advertised on condoms are based on laboratory results, not real life. The truth is that condoms are extremely easy to mis-use. One of the easiest ways to mis-use one is to first put it on upside down, realize your mistake, and turn it over to put it on correctly. Well, that leaves pre-ejaculate seminal fluid on the wrong side of the condom!
The church simply can not endorse condom use because it is not a fail-safe option.