I think it is wonderful that you voluntarily help in a homeless shelter. My beliefs lead me to search for the good in all people.
As do my beliefs. Well... sort of. I don't believe in good or evil. I believe that we're all just trying to get by in life. We all tell ourselves lies to help us cope. Some lies are more destructive than others. Whether an act is good or evil is an after-the-fact assessment. But I don't think people are motivated by either good or evil. Which means that people aren't inherently good or evil.
So I'd reformulate it. My beliefs lead me to search for the scared little confused child who years for love in all people. We've all got one. The hard part is to connect with it. That's what motivates me to volunteer at the homeless shelter. I think it's ultimately about my own exploration of myself. I do it to try to find what I have in common with these people. Turns out, quite a lot. And if it also leads me to helping people, great. I've a career climbing the corporate ladder, and I've been (in the middle-class capitalist sense) successful in life. I'm surrounded by people who struggle with staying humble and it limits them. It makes them fearful and weak. So work very hard on humbling myself. So volunteering at homeless shelters help. I approach every homeless person I meet (at the shelter) with the attitude that they can teach me things. In my head I elevate them above me. Makes my job there a hell of a lot more interesting, fun and rewarding. All this as a result of my faith (ie no faith).
And to yammer on about goodness. I think there's a danger in using the term "good" to describe people's nature. The way language works is that it works in dichotomies. As soon as you delineate and define you also exclude. If you call people good, you're also calling some people evil. It's impossible not to. It's just the way language works. If you say that all people are good, then you're saying nothing. If you have nothing to say, better to shut up, since you're just wasting everybody's time with nonsense.
This brings me to the category, of platitudes. I think they are extremely destructive. It allows people to believe they're doing good when they are doing nothing. It allows people to think of themselves as good people, even while they're hurting others. I'd put calling all people "good" in this category. There are better ways to say the same thing that doesn't exclude. Calling people good you start a mental exercise in people where they start looking for counter-examples, ie evil. Believing is seeing. If you give people the idea of good people they will start looking for and finding evil people all around them. And the worst thing is that it is automatic. We can't shut this off. So we should stop using the term good to describe people IMHO. People just do stuff to get by. It's motivated by neither good nor bad. It just is.