Utilitarianism isn't the only nonreligious, rational perspective on morality.
Actually, there aren't any purely rational perspectives on morality, as they all seem to hinge on preserving some intuition or another. But in terms of logically consistent, secular ethical frameworks which produce results most of us are comfortable with, utilitarianism isn't the only one on the list. And there are actually points where utilitarianism might end up producing results people aren't comfortable with (such as kidnapping people and killing them for their organs).
Actually, there aren't any purely rational perspectives on morality, as they all seem to hinge on preserving some intuition or another. But in terms of logically consistent, secular ethical frameworks which produce results most of us are comfortable with, utilitarianism isn't the only one on the list. And there are actually points where utilitarianism might end up producing results people aren't comfortable with (such as kidnapping people and killing them for their organs).