It is ideal to date someone in your faith and belief system. You have much more to talk and understand in that field, and will help your relationship.
However, your soul mate can come from anywhere really. A person earth life journey is such that one is placed in the circumstances that best suit what one comes to experience and learn. A high grace of the Almighty Father.
Your prayer and desire are to meet that SOUL-MATE, that will compliment you. Also, remember that marriage IS NOT for everyone. It is possible to be fulfilled without a spouse. All needs are met BY HIS GRACE, not all wants.