An argument gives supporting reasons why the point should be taken seriously. The reasons become the topic of mutual discussion or analysis. But if there are no reasons, there’s little to discuss. Opinions are opinions, not proof. A mere point of view cannot be taken seriously as worthy of belief.
People today tend to spout of assertions as if they're arguments. "Abortion is healthcare" or "you don't need God to be good" or "there's no evidence for Christianity" are often slogans hurled at people in debate, but they're not giving any actual reasons for their statements. Don't let them off the hook. Ask them to logically back up their claims.