From the 1830s, marriage has been a central and distinctive component of Mormon theology. Mormon teachings on marriage begins with the belief that, if performed by a person who has the requisite priesthood authority, a marriage may continue in the afterlife. Such a marriage is called a "celestial marriage" or a "temple marriage", and is a particular instance of a "sealing" which binds people together in the afterlife. Celestial marriage is considered to be a requirement for entry into the highest "degree" of the celestial kingdom (the highest degree of heaven in Latter Day Saint theology), and is thought to allow the participants to continue to have spirit children in the afterlife and become gods. According to Mormon belief, the continuance of a celestial marriage in the afterlife is contingent upon the couple remaining righteous.