The Jewish people were under the yoke of foreign oppressors ever since the Babylonian captivity. During the New Testament times the land of Israel was within the province of Syria and the tax collectors were collectors of Roman taxes, they were extortioners, and very despised.
The Jews detested these tax collectors not only on account of their abusive and tyrannical attitude, but because the very taxes that they were forced to collect by the Roman government were a badge of servitude and a constant reminder that God had forsaken His people. The tax collectors were always classed by the people with the harlots, usurers, gamblers, thieves, and dishonest herdsmen, who lived promiscuous, lawless lives. Some of the common terms for the tax collectors were "licensed robbers" and "beasts in human shape."
According to Rabbinism there was no hope for a tax collector. They were excluded from all religious fellowship including the Temple and Synagogue. Their money was considered tainted and it defiled anyone who accepted it. They could not serve as a witness in any court in Israel. The Rabbis had no word to describe any sort of help for the tax collector, because they expected him to externally conform to the law in order to be justified before God.
Ancient Jewish writings reveal some interesting views of Rabbis toward the tax collectors:
"As one robber disgraced his whole family, so one publican in a family; promises were not to be kept with murderers, thieves and publicans" -Nedar 3:4
"The synagogue alms box and the temple corban must not receive their alms" -Baba Kama 10:1
"It was not lawful to use riches received from them, as gotten by rapine; nor could they judge or give testimony in court -Sanhedr. 25, sec. 2
The attitude of Jesus toward the tax collectors was in stark contrast to that of the Rabbis. He had come to seek and save the lost. The Pharisees were separatists, and did not lower themselves to have anything to do with a tax collector, who was to them no better than a Gentile. But Jesus came not to condemn anyone, but to save every sinner and offer a better life. He never taught that there was anything inherently wrong with paying tribute to the Roman Government or collecting the tax. He was opposed to extortioners, but would fling open the door of repentance and salvation to them. He rejected none, not even the worst.
Jesus made himself a friend of men, even of the tax collectors and the worst of sinners. He set a new precedent among the Jews by accepting and associating with the tax collectors. He ate with them (Mark 2:16), He offered salvation to them (Luke 19:9), and He even chose a tax collector (Matthew) as one of His twelve disciples (Matt 9:9).
Luke 18:9-14 "Also He spoke this parable to some who trusted in themselves that they were righteous, and despised others: Two men went up to the temple to pray, one a Pharisee and the other a tax collector. The Pharisee stood and prayed thus with himself, 'God, I thank You that I am not like other men--extortioners, unjust, adulterers, or even as this tax collector. I fast twice a week; I give tithes of all that I possess.' And the tax collector, standing afar off, would not so much as raise his eyes to heaven, but beat his breast, saying, 'God, be merciful to me a sinner!' I tell you, this man went down to his house justified rather than the other; for everyone who exalts himself will be humbled, and he who humbles himself will be exalted."