For those of the Atheist persuasion, which is the worst case scenario? (details inside)

Your child comes to you and says they can no longer accept your way of thinking regarding God. Which would, in your opinion, be the worst choice they could make in deciding how to proceed with their lives; to become agnostic or to become religious? If religious, which would you consider the worst choice of the myriad available they could make?

Please note there is a separate question for those who are religious.