Greeks conversion to judaism.

How posibile was that in the past centuries rabbis to convert greek people in judaic religion! the ordodox is an amagalm of paganistic ones.
 
Since conversion happened it's obviously possible.
Especially as the total conflation of Judaism and Jewishness happened as a reaction against Christianity and Islam.
 
There are several problems with this sort of mass conversion to Judaism. Judaism is not missionary, never really has been but lets wave that one away. One of the "issues" that Christianity dealt with early on was the issue of Jewish law - circumcision, kosher food rules, and much more (613 mitzvot). The appearance of Christ and his dispensation of sin did away with that, making conversion much easier and Christianity is aggressively missionary. Islam does have some "rules" such as halal food (not as restrictive as kosher), no alcohol, and circumcision but less than Judaism. Islam was also aggressively missionary, spread by the sword especially against pagans more so than Christianity, and had formalized disabilities for non-Muslims especially pagans. Perhaps most importantly, Judaism was never the religion of the winners - either top down as in the later Roman Empire and gradually in Europe or the religion of the conquering armies.

For the average Joe or Jane in the ancient or early medieval world, most of the time the motivation for accepting a new religion was going along to get along. Sure there were cases of spiritual conversion, but for most this was not the case. When the new overlords made it clear it was in your best interest to convert, this tended to happen (no matter what religion you had before). Some conquerors, such as the Mongols, really didn't care what religion their subjects had, so you did not see mass conversion with Mongol conquest. Others, both Christian and Muslim, made acceptance of their religion a real plus for the newly conquered people.

IMHO to make one of these mass conversions to Judaism, and not just of an elite (like Khazaria), you need to make Judaism aggressively missionary, and seen as the religion of the winners.
 
Judaism, around the time of Christ WAS a proselytizing religion.

A lot of the early converts to Christianity were converted gentiles. So, OTL.

Note that the first (by a long shot) codified canon for Hebrew Scripture was the Septuagint - which was written in Greek. There were that many Greek speaking Jews.

---
Again, if you want most to convert, then, the OP's challenge could be OTL, depending on your definitions/how hard you squint at the problem. Christianity was originally considered simply a sect of Judaism.

Classical Judaism, with all the rules and requiring male converts to be circumcised, is unlikely to take over the Roman Empire, but a looser sect (possibly closer than Christianity) has a very good chance.
 
Bit of a left-field suggestion but I read somewhere that there were attempts to convert the first Bulgarian Empire to Judaism before they went Christian. Let's say that that goes through, along with a little extra wanking of the Khazars, and eventually a Jewish Bulgar-Khazar alliance (along with whoever else they can get to go Jewish) succeeds in overrunning the Byzantine Empire. In the aftermath you could see a lot of Greeks converting to Judaism.
 
Top