"Then cometh Jesus from Galilee to Jordon unto John, to be baptized of him. But John forbad him, saying I have need to be baptized of thee,
and comest thou to me? And Jesus answered him, Suffer it to be so now:  for thus it becometh us to fulfill all righteousness.  Then he suffered him."
Matt. 3:14-14

This is the great commission...
"Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the
end of the world.
Amen"  Matt. 28:19-20

Perhaps there is a need to define what is meant by an "ordinance."
 An ordinance means an action which was commanded by Christ, and that was to be obeyed by His followers. The scriptures tell us that Christ ordained the following acts to be observed by His followers.

We will be considering these three ordinances and the reason or purpose for these instructions to be observed within
the Body of Christ.

* Baptism  
* Our Lord's Supper
*Washing of the saint's feet

Our Lord commanded these actions throughout all time. These ordinances were to be propagated from generation to generation until Christ returns for His own.
These actions are not "optional" as we shall relate through the scriptures
their purpose and meaning for
 ALL Christians to observe.
 
Let us consider the full meaning and understanding then of "Baptism."