If there is no God as Judeo-Christian religions understand Him, life is a meaningless random event. You and I are no more significant, our existence has no more meaning, than that of a rock on Mars. The only difference between us and Martian rocks is that we need to believe our existence has significance.
Now to the second objection, that you don't need religion or Judeo-Christian values, just a belief in God or, as is more popular today, in "spirituality" to imbue existence with meaning. Theoretically, one can posit the existence of the God of Judeo-Christian religions without actually believing in any of those religions or in any of their holy works. There is, however, some absurdity in believing in the God made known through texts whose authenticity one rejects. "I believe in the God made known to the world solely through the Old Testament but not in the Old Testament" is not logically compelling.
Whatever the logical inconsistencies or theoretical arguments in either direction, the fact remains that while secular individuals can believe that their own lives have meaning, secularism by definition denies that life has meaning. The consequences have been devastating to mental health and to social order.
Among these have been increased unhappiness and depression, increased reliance on drugs and numbing entertainment to get people through life, moral confusion, belief in nonsense (such as Marxism, fascism, communism, male-female sameness, pacifism, moral equivalence of good and bad societies, and much more), and perhaps most ubiquitous, political meaning as a substitute for religious meaning.
Given that the need for meaning transcends all other human needs, its absence must create havoc individually and societally. In government, secularism is a blessing; but most everywhere else it is not.
Dennis Prager is a SRN radio show host, contributing columnist for Townhall.com and author of his newest book, “The Ten Commandments: Still the Best Moral Code.”