When they claim to hold faith in a god and then go on to espouse morals that align with their interpretation of their religious belief, then sure. They don't need to say "because of my religion" when they have offered up a preface
“Every great religion in the world, Christianity, Judaism, Islam, Buddhism, others, essentially comes down to Do unto others as you would like them to do unto you. And what I have believed my whole life – I believed it when I was a 22 year old getting arrested in Chicago protesting segregation – that at some level we are all in this together. When you hurt, I hurt. And when my kids hurt, you hurt. And it is very easy to turn out backs on kids who are hungry and veterans who are sleeping out in the street and we can develop a psychology that says ‘I don’t have to worry about them, all I got to worry about is how I can make another five billion dollars. But I believe that everybody in this room impacts everybody else in all kinds of ways that we can’t even understand, its beyond intellect. It’s a spiritual, emotional thing. When we do the right thing, when we treat one another with respect and dignity, I think we are more human. That’s my religion, that’s what I believe in.” Bernie Sanders