From The Pixar Touch, by David A. Price:

Andrew Stanton, Co-Director of Finding Nemo, “…also spoke of a spiritual aspect to the relationship of Marlin and Dory. Dory was, literally, an angel fish. ‘The protagonist’s battle was to overcome fear by discovering faith, and certainly Dory represented the angel, or the helper who showed him how to let go and not be consumed by his worries,’ he told an interviewer for a Christian-oriented film web site.
He observed that subtlety is critical in giving films such as Pixar’s a spiritual or religious dimension. ‘My personal view is that if you go into things on a pulpit or with an agenda in the creative world, it can easily get in the way of your creativity and quality… Be Christ-like in everything you do, not worrying about whether you’re furthering the cause.’”