How would John's baptism have offended a Jew's national pride? It is my belief do to the fact that baptism by immersion was associated with people from other nations whom desired to become a proselyte this would have offended a Jew, and most certainly the leadership. In the minds of those who chose not to come unto the baptism of repentance they did not need to. They were blind by a perceived title of entitlement and pride. In their minds why should they confess, what were they to repent of. They followed the Law (in their understanding); they were of Abraham.
confessing their sins (Proverbs 28:12)In Matthew ,3 baptism was used as an outward sign of repentance and forgiveness, identifying with the message John preached. History tells us that the Hebrews were familiar with washing in regards to cleansing (Exodus 30:17-21 repeated washing , wash, Ezekiel 36:25). Spoken word (Talmud) and history tells us they were familiar with baptism of proselytes from heathenism (self immersion). This baptism was not simply following what had been practiced, it placed the hearer Jewish and non-Jew at the same circumstance, challenging them REPENT, start all over.
To ask them to baptize as did the proselyte (gentiles), a stranger who desired to be adopted into the family of Israel was offensive to them in their minds.
Who welcomed John's baptism? Jesus, Scripture tells us that Jesus knew no sin, so why did Jesus ask to be baptized? The words for thus it becometh us to fulfil all righteousness imply that it was necessary for the plan of God.
Truthfully only Christ knows, however we can speculate some good reasons He did: He was advancing God's work - He did not stand as an onlooker as did the Pharisees & Sadducees - He was endorsing the call of John the Baptizer - He by His actions was confessing the sins on behalf of the nation - He was identifying with the penitent people of God - He was giving an example to those afterwards (to include us) - He was obedient to the Father. Lastly there was no particular precept in the Old Testament requiring a Hebrew to be baptized by immersion. Although Jesus was not after the Levitical priesthood, Scripture declares Him as High Priest. As the high priest was initiated into His office by washing and anointing, so must Jesus. Therefore although without sin He was baptized, washed, and anointed by the Holy Ghost. By doing so He fulfilled the righteous ordinance of His initiation into the office of high priest, and thus was prepared (preparing) to make an atonement for the sins of mankind.
Who resisted it? The Pharisees, the Sadducees and those they influenced
Why? I believe the main reason was FLESH, pride. The common teaching of that day said that the Jews participated in the merits of Abraham, which made their prayers acceptable, helped in war, expiated sins, appeased the wrath of God, and assured a share in God's eternal Kingdom. Prophetically the mentioned are true, (Abraham believed God) just as one must believe and have a personal relationship with God, they must also repent of their own sins. Consequently John and Jesus preached the necessity of personal repentance.