The statement "I'm spiritual, but NOT religious." is merely a dodge to cover for NOT living under any authority that morally obligates one.
Be careful. The claim that Christianity is not a religion has it's origin in a Protestant mindset that precisely rejects the authority of the Church in favor of an individual relationship with God alone. The meaning of the word 'religion' comes from the Latin meaning "to bind" someone (it's same root as the term ligament). The Catholic faith is indeed binding on everyone. The actual way to look at it is that Christianity is what the Scholastic theologians called "right religion." All other systems are false religions!