belief system and values are different. if you are referring to beliefs as values, then you kow what to do. Like the post above says, it is absolutely necessary to share the same value sets if you are talking of a life-time partnership (its ok to differ on other aspects that are not reflective of your values).
Like someone said, marriage is about being able to relate to one another at emotional, physical but most of all- on the spiritual plane. While the last factor by itself is sufficient sometimes BUT the first two factors without the third one are indicative of a potential break-down case.