Can moral and ethical principles be arrived at through reason alone? Or is some kind faith or dogma needed? Is the only moral outlook available to the atheist moral relativism?

Last philosophical/religious question of the day. :)

Please note that all these questions are intended to be open-ended. I have my own ideas, but I’m not here to argue against the answers or shut down any of them. I’m welcoming all answers. If you don’t like the question, explain why.