In Matthew 23 we find the famous Seven Woes with which Jesus publicly indicted the scribes and Pharisees for their hypocrisy and arrogance. The second of these woes condemns their missionary practices, reading as follows:
"Woe to you, scribes and Pharisees, hypocrites! For you travel across sea and land to make a single proselyte, and when he becomes a proselyte, you make him twice as much a child of hell (gehenna) as yourselves." (Matt. 23:15)
The Greek word proselytos refers to Gentiles who officially converted to Judaism by undergoing circumcision (for males) and agreeing to abide by the Law of Moses. Now, is noteworthy that most orthodox Jews today do not actively seek out Gentile converts. For instance, in a recorded lecture, the late Dr. Leonard Tann, a senior British rabbi in Birmingham, England, explained that in England it is only the Chief Rabbi's Office in London that can approve conversions. Moreover, he himself followed the practice of Naomi (Ruth 1:8-15) in bluntly discouraging would-be proselytes at least three times before agreeing to assist them in converting to Judaism.
However, Jesus' statement here agrees with other historical evidence indicating that the sect of the Pharisees were very active in seeking proselytes at this time. It is apparent that the writings of the first century Jewish historian Josephus (himself a Pharisee) were intended to commend Judaism to his Gentile readers. Indeed, a recent book by Michael Bird which takes its title from Matt. 23:15 argues that Jews of this period were active in evangelizing the Gentiles, both in Palestine and the diaspora.
It has been argued that much of the Pharisees' activity was aimed at converting loose adherents to Judaism (the so-called 'proselytes of the gate') to their stringent brand of religion. The Pharisees compelled people to follow not only the Law of Moses itself but also the many layers of oral law which had been added over the centuries. For this reason, Paul referred to the Pharisees as "the strictest party within our religion" (Acts 26:5).
It seems that the Pharisees thought they had the perfect religion: they had worked out a foolproof formula through which they could ensure that they were following God's laws and thus earning salvation, while their consciences could be put on autopilot!
While we don't have any historical narratives of Pharisees proselytizing in the New Testament, we do have plenty of evidence that they were willing to travel significant distances to oppose non-Pharisaical practices. The Pharisee Saul unilaterally sought permission from the high priest to travel from Jerusalem to Damascus to arrest Christians (Acts 9:1-2). Jews came from Antioch and Iconium to Lystra to oppose Paul and have him stoned (Acts 14:19). Jews came from Thessalonica to Berea to oppose Paul (Acts 17:13). Jewish Christians (possibly Pharisees) came from Judea to Antioch to impose circumcision on the Gentile Christians (Acts 15:1-5).
Thus we can see that many Jews, and the Pharisees in particular, were zealous for stamping out any form of Judaism which did not measure up to their legalistic standards. From Matt. 23:15 we can infer that they took the same elitist zeal to their efforts to proselytize Gentiles.
Jesus' emphasis on travelling over sea and land to make a single proselyte suggests that the scribes and Pharisees may have been very picky missionaries. We know they looked with disdain on some classes of people (Matt. 9:11; Luke 7:39; Luke 15:2; Luke 18:9-11). They probably did not see the fields as 'white unto harvest' but rather sought to find a few needles in the haystack. They would probably have written off many as unworthy of their religion based on profession, socioeconomic status, illiteracy and other superficial reasons.
However, their strict law-and-order, salvation-by-merit message would certainly have resonated with some, bringing a sense of purpose and fulfilment. And for Jesus, that was the real tragedy. Once he learns that the formula for righteousness and salvation is strict legalism, the proselyte's zeal may well surpass that of his teachers. He will seek to impress his loyalty upon them by going to further extremes than they ever did. In this way, religious extremism is self-replicating. As D.A. Carson wrote in his commentary on Matthew, “The Pharisees’ interpretations and the rules deduced from Scripture became so fully those of their converts that they ‘out-Phariseed’ the Pharisees” (Matthew & Mark, Longman & Garland, eds,. 2010 p. 538).
Pharisaism with respect to the Torah and oral law is not a major problem in the church today. So is there any lesson in Jesus' words for us in 2013? I think so. Jesus' words apply equally to all those who proclaim that only those who belong to their group, who assent to their statement of faith, who follow their rules, can be saved. They say, in effect, "Come to us!" rather than "Come to Him!"
As soon as the focus turns from the Saviour to the religious system, we have laid another foundation instead of what has been laid - Jesus Christ (1 Cor. 3:11). And, if we succeed in winning converts to our ideology, they may soon turn on us once they determine that our religion is not as perfect as it could be. This is the fate of all who seek to construct their own way to salvation rather than simply believing in the Way (John 14:6). Their religious structures soon bear little resemblance to faith in Christ Jesus, but consign both founders and converts to the destiny laid out by Jesus in those frightful words, "child of hell."