Why was Jesus baptized? What does the phrase "to fulfill all righteousness" mean?

“John would have prevented him, saying, 'I need to be baptized by you, and do you come to me?'

But Jesus answered him, 'Let it be so now, for thus it is fitting for us to fulfill all righteousness.' Then he consented” (Matt 3:14-15).

Many have questioned why Jesus was baptized, especially if John's baptism was one of repentance. For what would Jesus have to repent of if He was sinless? Some commentators point to the following verses where “the heavens were opened” for an answer, stating that when God declared “This is my beloved Son, with whom I am well pleased,” Jesus was publicly declared as God's son and marked the start of His ministry. Thus, it was by means of John's Baptism that Jesus was broadcast to the world to be the Son of God (a theme in Matthew's gospel), and hence Christ's words indicate baptism was a right that John and Jesus needed to fulfill (Sailhaimer, 438). While nothing is biblically wrong with this conclusion, it seems to be a veiled attempt to promote the authors theological view on baptism as a symbolic public declaration of faith (which I agree with). Sadly the commentators theological agenda (even for good theology!) overlooks the crucial significance of Christ's words and His baptism, which actually gives the symbolic act of baptism any meaning!

---

Jesus words and His subsequent baptism by John are an adumbration, or veiled allusion, of the cross, Christ's mission. For Jesus to have sought John's baptism at all would have required “significant motivation and suggests that Jesus was already aware of God's special purpose for him” to make the seventy mile trek (especially if on foot!) from Nazareth (France, 119)1. Other commentators accurately capture the meaning of Jesus' words, that “with John's cooperation, [Jesus] is to do all that is right for the completion of his mission.” The act of the baptism, the descending of the Spirit, and God's words foreshadow “Jesus' bearing the iniquities of the ungodly” (Elwell, 727). The fact the Jesus uses the word “fulfill” (a word used to signify completion of God's word) also suggests that Christ's baptism plays a vital role in carrying out His God given “specific mission” (France, 120). Even Catholic commentators (who typically disagree strongly with Protestants on baptism) uphold that Matthew has the saving activity of God in mind, where “to fulfill all righteousness” means “to submit to the plan of God for the salvation of the human race...[which] involves Jesus' identification with sinners” (New American Bible)2. Thus, “to fulfill all righteousness” is Christ's full conformity to God's holy character and obedience to the righteousness will of His Father and His Father's mission (Howell, 30). Through baptism the fully human Christ fully identifies with sinners in every way (except for sin) even being baptized with our baptism and tempted with our temptations to demonstrate that He has come as a suffering servant on a redemptive mission as fully God to serve as man's sinless substitute. 

Only once we understand the significance and purpose of Christ's baptism can we understand the significance and purpose of a believer's baptism. For without the suffering Servant's (Isaiah 52:13-53:12) allusion to the cross and God's declaration of His work to one day subdue the nations (Psalm 2:8-12) and release the captives from sin (Isaiah 42:2-7), baptism is meaningless. This is why Paul links our baptism to the death and resurrection of Christ (Romans 6-3-4), “for if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his” (v5).

• Elwell, Walter. A.. Evangelical Commentary on the Bible. Grand Rapids: Baker Book House. 1989.
  
• Sailhamier, John. H. NIV Compact Bible Commentary. Grand Rapids: Zondervan. 1994.
  
• Howell Jr., Don N.. The Passion of the Servant. Eugene: Wipf & Stock - Resource Publications. 2009.
• France, R.T.. The New International Commentary on the New Testament: The Gospel of Matthew. Grand Rapids: Eerdmans Publishing Co. 2007.
• The New American Bible. Canada. World Catholic Press. 1987. 1013. (will try to find better Catholic source)