"In the ordinances thereof, the power of godliness is manifest." (Doctrine and Covenants 84:20)
"Ordinance" is defined as the action of ordaining, ordering or arranging. It is the action or process of making ready, preparing or providing. It is "a practice or usage authoritatively enjoined, especially a religious or ceremonial observance, as the sacraments, particularly applied to the Sacrament of the Lord's Supper" (Oxford English Dictionary).
The Church of Jesus Christ of Latter-day Saints defines ordinances as "a sacred, formal act performed by the authority of the priesthood. Some ordinances are essential to our exaltation. These ordinances are called saving ordinances. They include baptism, confirmation, ordination to the Melchizedek Priesthood (for men), the temple endowment and the marriage sealing. With each of these ordinances, we enter into solemn covenants with the Lord" (topic definition from www.lds.org).
Elder Dennis Neuenschwander of the Seventy spoke very thoughtfully about ordinances and covenants.
"In a very broad sense, everything ordained and established by God's authority with the intent that it be applied in the lives of His children may be referred to as His ordinances. Consequently, the commandments, statutes, decrees, and requirements of God are properly defined as the ordinances of God. Understood in a somewhat narrower sense, ordinances are also solemn acts or ceremonies that have very specific sacred and holy purposes, significance, and meaning. My reference to ordinances is in this narrower application.
"Sacred ordinances and the divine authority to administer them did not begin with the Restoration of the gospel and the founding of the modern Church in 1830. The sacred ordinances of the gospel as requirements for salvation and exaltation were 'instituted from before the foundation of the world.'
"Sacred ordinances and knowledge of God are closely related. As sacred ordinances reveal the order of the kingdom of God in a progressive manner, our participation in them reveals to us a knowledge of the personality and character of God that can be gained in no other way" (Ensign, August 2001), for "without the ordinances (administered by the Melchizedek Priesthood), and the authority of the priesthood, the power of godliness is not manifest unto men in the flesh" (D&C 84:21).
Indeed, the restoration of the ordinances was an essential element of the Restoration of the gospel, "For they have strayed from mine ordinances, and have broken mine everlasting covenant" (D&C 1:15).
Participation in these saving ordinances is necessary but not sufficient for our salvation. It is clear throughout all scripture that it is our hearts that the Lord is concerned with. For redemption comes "in and through the Holy Messiah … unto all those who have a broken heart and a contrite spirit; and unto none else can the ends of the law be answered" (2 Nephi 2:6-7).