Whoops. Always gotta start with a caveat. I've looked into a lot of different practices from a lot of different angles. Sometimes I know that I sound here like a practical humanist and sometimes like a Roman Catholic. I don't mean to propound any particular faith/religion/practice. For me, a big part of ultimate truth is that it's personal. What's right for me may not be right for you. So I use examples that I think may strike people as familiar and so be more powerful, but I claim no particular current affiliation.

Faith.
By definition, it requires not knowing. If you know something is factually true, then you don't have faith, you have knowledge. If you believe something to a moral certainty and don't have the facts to back it up, that's faith. They say that part of the beauty of faith is the "not knowing." I'm currently in the midst of a "Don't Know" practice, myself. Just letting go into an ability to say, "Well, I don't know," is a wonderful, liberating thing on a very deep, personal level. Same thing has got to stand true of someone who says, "Sure, I don't KNOW that if I practice this or that religion, I will be saved/go to heaven/whatever whatever, but I have FAITH that this is the right path for me." Our old friend Doubting Thomas had to plunge his hands into Christ's wounds in order to believe that the man standing before him was the man he knew. Everyone has a line past which they can't travel without help. Maybe for BurbKnight, archeological digs and prophecies take him across the line. Maybe for other folks, nothing will do other than personal divine revelation. For some people, there's an inner voice that says, "It's okay to stop asking whether it's true now." and that's the point at which they let their intellectual minds go and follow their heart. Everyone is different. You'll find your path. That's pretty much guaranteed by the fact that you're looking. Only thing is, remember it's a path, not a destination. All religious teachings, whether or not they have a dangling carrot like "heaven" or "nirvana" or whatever, are about how to get on a path, how to conduct a search.

Another thing that I've noticed consistently is that as part of the maturation process, we all step back from our cradle religion and re-assess. Sometimes we return to the religion we were raised in, only now we're doing it with an adult's perspective. For example, the stuff they teach to kids in Sunday School is pretty watered down. You have to be an adult to really get the unexpurgated version of a religion. Sometimes we step back and decide that our parents' religion doesn't create the community that we need in which to flourish and grow. Then we'll strike out on our own, away from the family. Sometimes we change religions as a means of stepping back from our families (because we go through the same reassessment process with families as we do with religion. That's all part of becoming an adult. And that's why adolescents are known to be "rebellious" - they've begun the process).

Motivations.
When I decided that it was time for me to do volunteer work, I decided that the best thing for me to do, the work that fulfilled me the most, was hospice volunteer work. People, friends, family would hear that I was spending time with people who were dying and a lot of them would say, "Oh, that's so brave" or "that must be really hard," or "you must be such a good person" or "how selfless of you." But of course the truth was that I wasn't a better person for doing it than anyone else is for doing or not doing what they can. And the truth was that it probably would have been really hard for some people, but it was right for me, so it wasn't hard. And I had all the best intentions of being selfless when I started, but no matter how much I gave, I got more back. So then I would try to be even more giving, because I wanted those scales to balance out at "janey's a giving person" but I kept getting MORE back. So I just think I got way more out of it than I ever gave. But does that make me a selfish person? It was a happy by product of doing something that was a good fit for me (I also credit that a big part of my motivation was selflessness for spiritual growth. I didn't get the selflessness, but it helped me become much more aware, conscious and loving).

So what I've noticed is that it's all part of the soup. Questioning, seeking, looking for one's own ulterior motives, asking whether faith is enough, asking whether knowledge is enough, asking whether this or that community is right, asking what lies ahead. Looking at what's right here, right now. Looking at what came before. Life as spiritual practice. What your "practice" (i.e., religion) is is only a part of your life, but everything everything you do is part of your spiritual seeking/finding.

Peace.