Why is it that Orthodox Jews are so prejudice towards Messianic Jews but to Atheist Jews they are so lenient? Such Hypocrisy and insecurity. They are even considerate towards Lubivicter adherents which is much worse that the Atheist.
It isn't just Orthodox Jews, it is Jews in general, even the secular.
Why? A couple of reasons. One is undoubtedly the historic
atrocities Chrisitanity has perpetuated upon Jews. This of course
is in the past, but memories and feelings run deep and even the
most secular of Jews has an innate bad reaction when a Jew
becomes a Christian. I don't think it is something that a non-Jew
is able to understand, so I won't try to go further other than to
say that it exists.
The next point I shall try to put delicately, so I apologize in
advance if it comes across harshly. Jews who are secular are
not observant but they have not transgressed into avodah zarah,
whereas a Jew who becomes a Christian has. He has commited
one of the worse sins (indeed, one of three you can not
do even to save your life) a Jew can commit. A Jew who has
become a member or another faith has cut himself off from his
people and from HaShem, where as a secular Jew has not yet
lost that connection.
As for the Lubavitchers, a small minority of them believe the
blasphamy that the Rebbe was moshiach and they are working
at eradicating this belief. Many, many groups have condemmed
them for this belief (the OU and Agudath Israel are two major ones) , and it has caused them much damage and
isolation in Jewish communities. They are not the first, nor
unfortunately probably not the last, Jews to follow a false
moshiach. Hopefully they will resolve this issue soon.
This is an honest attempt to answer your questions, and I
hope it does not cause offense.

Chava
You have a lot of chutzpah. You're one of those Jews who comes on here just to disagree with Messianic Judaism half the time, anyway. If you want to be honest, Sheitl "Queen" (and you need to get off your pedestal), non-Messianic Jews are being stubborn, hard-hearted persecuters, just as Y'shua HaMashiach who is Jesus Christ said you would be. You tolerate everyone else but Jews and Gentiles who are Messianic.
I have seen enough persecution of JFJ and Messianics to say, "If you're not Messianic, don't act like you can relate a darn to Messianics. Until you seek to understand the Bible over your own traditions, just leave Messianics to counsel and relate to fellow Messianics."