There is no evidence that suggests spirituality can cure OCD. And, as noted in past questions, therapists do not really talk about curing OCD as much as learning to live with and handle it.
Although there have been some recent discussions in the media about the positive effect prayer has on healing, the most recent study (Study of the Therapeutic Effects of Intercessory Prayer (STEP) by Benson, et al. (2006)), shows that there may actually be a negative impact on health when people know that they are being prayed for.
So, there is no conclusive evidence in either direction about whether spirituality can be helpful in overcoming OCD.
That said, the best way to work toward improvement is having belief in yourself and faith that you can improve and that your OCD will not be in control of you. This belief can be a touchstone to help you push through your therapy exercises and deal with any setbacks that you may have along the way.
If you approach therapy with a positive attitude, you have a better chance of seeing improvement; if you think that therapy will not work for you, you will most likely encounter treatment failure.