I read most of Yalom's The Gift of Therapy. He mentions religion a couple of times in his book and a few of them, his own opinions on the matter are quite clear. While I grew up in a semi-religious household, I see myself as agnostic or spiritual. Religion, I think, is a wasted doctrine that has no singular value. Its meaning is lost to re-telling and outside opinion. Religion could be anything - money, a deity, the rain, science... whatever. I would rather put my faith in something I can stack in my favor - people.
That being said, I would like to apply religion to the four constants in existential psychotherapy. These include death, freedom, isolation, and meaninglessness. Death is simply the fact that someone (everyone) will die. It is an inevitability. Freedom actually refers to freedom of responsibility/choice; everyone has the ability (or perhaps better put, the possibility) of making choices and having responsibility over themselves. Isolation is intended to mean that everyone in the world is alone. The last term, meaninglessness, is perhaps the most important and sought after ideal of the list. People need meaning to survive. They need a reason to live.
Religion drastically changes the meaning of death. To a certain degree, the act of dying changes from an inevitable end to a portal to some other plane (whether that be Paradise or Pit). It causes many to decry finding meaning in his own life for that in another. Death becomes just another tick on a timeline. The budding scientist in me scoffs at the idea of such a belief in something that cannot be documented.
Freedom in and of itself becomes meaningless (especially in Western religions) because everything is pre-ordained. People don't have control of their lives anymore. This means that piously religious folk trust everything to their faith, making decisions that are important or everyday not their problem.
Isolation, that feeling of being alone, which makes us all connect with one another becomes a farce because we're never alone. People can live with their religion instead of each other. The idea of dying alone also becomes defunct.
Meaning. Now isn't that what religion (and philosophy) are all about? Why are we here? Rather than figuring out our own meaning (or perhaps coming to the end conclusion that a search for meaning is itself meaningless), religion gives us false hope. It tells people that their meaning is the same as everyone else's... Is that true? Is everyone the same as everyone else? That's doubtful.