First: Jews killed Jesus and our economy?? on what planet is this even remotely Biblical? Jesus dies willingly in order to become the perfect , spotless lamb, the blood sacrifice for our sins- everyone that sinned had a part in the nails that were driven in the hands of Yeshua.
The economy- our greedy government and lack of restraint has killed our economy (and most of those in our government claim to be Christian) so do with that what you will. . .
Second, what Jewish 'things' are you talking about? If you mean the laws and feasts ordained by God, tell me where in the Bible it says that these are "Jewish things" and what Christian does not believe in them? Most Christians do not practice them because they errantly believe they were for salvation and Jesus came and changed that- again, not Biblical. these "Jewish things" you speak of are not Jewish at all, but God ordained- they were practiced and followed to the letter by Jesus and were set in place to give us a pattern, instruction, a standard for the way to live to keep ourselves healthy, protected and prosperous- one should not follow them to be saved but because they are saved by the blood of Yeshua.
Messianic Jews are not half Christian- they DO NOT mix paganism with God's word and call it holy as do the modern Christians, they DO NOTthrow out God's laws saying we are free from law only to set in place and hold over the heads of others their own laws and standards as do modern Christians.
Messianic Jews are simply Jewish people who have come to understand that Jesus/ Yeshua is the messiah promised from the very beginnings of creation- they continue to follow the ordinances and observe the feasts set forth by the same God who promised and the same God who sent the Messiah, Jesus- they have not turned away from God or His commands.
It is Christians who say they follow Christ but take a different path, a path of paganism and lawlessness that God did not ordain, a path that Jesus did not walk. . . it is modern Christianity that we should be concerned is misrepresenting itself- you cannot 'follow someone if you refuse to walk where they walked'