We nailed him to a cross then, but now we have
nukes. However, there is more that can be said as to why
Christ would die this time.
Imagine Christ comes back to Earth after over two thousand years of chilling up in Heaven. The centuries of waiting is now over. However, how could Christ be treated here on Earth? What would happen around the world?
In Waco, Texas there was a man named David Koresh. This man believed that he was the Messiah. The FBI and ATF stepped in because they believed Koresh was hoarding machine guns. This backed the following into a compound for a 51-day standoff. The eventual outcome of this was a federal tank attacking the compound and the 86 members of the following killing themselves in a fire. Basically, the United States federal government killed 'the Messiah' because he was a threat to them. And the United States is primarily Christian.
As for the dogmatic Catholic Church, what would the Pope say? How could the Catholic Church, after centuries of never budging on any issue, recognize the Second Coming? I assume the church wouldn't go as far as it did with the Spanish Inquisition and put Christ to death, but they would at least not accept the Second Coming and cast off Christ.
What about non-Christians? I doubt that the second coming of a Christian diety would be overlooked by those of other religions. The Second Coming would symbolize a threat to their power. Non-Christian fundamentalists the world over would stop at nothing to kill Christ.
It seems that Christ would be targeted not only by non-Christians, but Christians as well. When Christ came two thousand years ago the Jews put him to death. The class that was supposed to be his following. The Romans didn't care, they ruled the world. Jesus was just another man to them. However, in the current state of affairs, Christ would be condemned by the church he represented and scorned by persons of all religions, some of which would attempt to kill him.