Do Jews consider messianic Jews to be blasphemers?

If a Jew becomes a Christian, they are a Christian (or an apostate as far as being Jewish is concerned). We still believe that all people who do good (good works, charity, treat others well, etc.) have a place in the world to come. Those that believe in Jesus and STILL call themselves Jewish are at best, misguided, and at worst, deceitful. One cannot be Jewish and believe in a Moshiach (Messiah) that did not fulfill our prophecies.