The Crowd Scene

If you're going to make up false stories that include real dates, real locations, and real public figures that can be checked out, it would make sense to wait until all of the eyewitnesses that can prove you wrong are dead. However, all of the New Testament documents are written within the lifetime of the eyewitnesses. All scholars will now say that the gospels were written around 70A.D. The epistle of Paul dates to about 20 years after Jesus' death. The 1 Corinthians Creed implicating over 500 witnesses was a public letter circulating only 20-25 years after the events and states plainly that many of those witnesses were still around to be verified:

1 Corinthians 15:3
For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures, that he was buried, that he was raised on the third day according to the Scriptures, and that he appeared to Peter, and then to the Twelve. After that, he appeared to more than five hundred of the brothers at the same time, most of whom are still living, though some have fallen asleep. Then he appeared to James, then to all the apostles, and last of all he appeared to me also, as to one abnormally born.

Tim Keller