You are confusing "moral" with "meaningful". Does being "moral", as defined by the codes of your religion, provide your life with meaning? You may be right that morality cannot be objectively defined (I can't do it, so I'll give you that point) - but that does not mean that it requires a religion or a deity to define it subjectively. Anyone could just as easily define morality as, for example, "murder is wrong on Thursdays" or "murder is wrong unless you are murdering an infidel / rapist / Yankees' fan / whatever". That morality could be based on anything; no religion / deity required.
Similarly, perhaps some people believe life would be meaningless without God. I disagree - my life is plenty meaningful to me.