Do people just want a quick route to heaven?

I mean, Christianity just says that if you are whole-heatedly repentant of your sins, even if it ****** up the lives of millions of people big time, you will still get to heaven, and likewise, the popular Japanese Judo-shu sect of Buddhism states that if you repeat the mantra, 'Namo Amida Butsu' you will enter Pure Land (Something that I am quite sure doesn't exist in the Chinese Pureland Sect). So, why is actually doing good deeds dropped in favor of 'repenting wholeheartedly and enter the pearly gates'?