Well, personal religious choices should not change based on what other people think. It should between you and God only.
With that said, I think a Christian converting to Judaism is missing out. Judaism has great traditions and celebrations and there is a lot we, as Christians, could learn from them. But Judaism is looking for their Messiah to come; Christians recognized that he already has, Jesus. It comes down to who you think Jesus was and is. He couldn't have just been a great teacher or prophet- otherwise he'd be a liar and a lunatic based of the claims he made. Where his claims true?
I believe so. He is the fulfillment of the Torah, the law of moses.
they probably were not a true Christian. Some religions think they are Christian when in fact they are just religious, they have not accepted Jesus as their personal Savior and Lord. To be a genuine Christian a person needs to be given a new spirit... a new human spirit with the life and nature of God. This is only possible by accepting Jesus as your Lord and Savior. there are those who think that if they are NOT a Jew they are a Christian... not so.
It is difficult, but a full and rewarding change. You have to be willing to lose everything, your friends, family and life style.But you are not required to make these changes. All G*D requires of you to be considered righteous and have an equal share in the world to come is to keep these universal laws.
* To behave justly in all relationships, and to establish courts of justice.
* To refrain from blaspheming Gods name.
* To refrain from practicing idolatry.
* To avoid immoral practices, specifically incest and adultery.
* To avoid shedding the blood of ones fellow man.
* To refrain from robbing ones fellow man.
* To refrain from eating a limb torn from a live animal.
Not true Rabbit.Ruth converted and she was David's grandmother. Exodus 23:9 tells us not to oppress the stranger in our midst. The Noachides actually worshiped with us.
As long as it's done for the right reasons, I'm fine with it. The Jewish people have an everlasting covenant with God, and we Christians should *respect* that covenant just as much as we respect our own, even if we (naturally) prefer our own covenant to the covenant that God has created between himself and the Jewish people.
That being said, the "right reasons" are religious reasons - that is, that a Christian authentically prefers to live according to the Mosaic Covenant rather than according to the Christian Covenant. An example of a "wrong" reason: so that a Jewish person whom you love will agree to marry you. This is not in service of God, but rather in service of oneself. Similarly, if a Jewish person converted to Christianity for the sake of gaining a spouse I would also consider it to be the "wrong" reason.