Why is faith so much more important than being a good person?

I recently had a debate with one of my friends in which he asked "Why would a good and just God not make salvation dependent on ethics, but rather on gullibility, as the Christian God has?" and I couldn't provide him with an honestly good answer, and in fact it's a question that I need an answer to as well. In Christian teaching we are taught that 'man is saved through faith and grace' and while there are scriptures that put emphasis on morality and service, that aspect seems to downplayed, and in fact there are some denominations in which you can be saved wholly by faith. What I'm getting at is that Morality seems to play a Robin to Faiths Batman. Is morality really important in Christianity?