Former Newsweek reporter Susan Katz Miller suggests that modern families shouldn't limit their children to a single binding faith. As a guest on my radio show, she discussed her book "Being both: Embracing two religions in one interfaith community" and denied that such families take both religions less seriously. Though claiming that she and her husband were simultaneously committed to Christianity and Judaism, she admitted she didn't believe that Jesus was Lord and Savior, and didn't feel commandments of the Torah counted as binding directives for her.
Of course, it's appropriate to raise kids to respect other religions, but if all faiths apply equally that guarantees confusion more than tolerance. If no religion counts as more true than others, than none of them offer a compelling path to truth or holiness. Being both most often means being nothing.