The Discovery Channel claims that they are not trying to destroy Christianity with their documentary. They think that it will strengthen Christianity:

According to Discovery, the movie does not challenge Christian beliefs. Spokesmen for the network argue it actually buttresses some doctrines.
Representatives for the channel were unavailable Tuesday, but in a statement on its website, the network says that “if Jesus’ mortal remains have been found, this would contradict the idea of a physical ascension [into Heaven] but not the idea of a spiritual ascension,” adding that the latter is consistent with Christian theology.
In a news conference hosted by Discovery Channel to promote the film, Dr. James Charlesworth, a professor of New Testament language and literature at Princeton Theological Seminary, said the findings could help Christian doctrine by combating heretic teachings that Christ was not fully human.
If the findings are accurate, Charlesworth said, “we’re finding a basis for Christian hope and vision indeed the Christian affirms that Jesus was fully God and fully human.”

This is not Christianity as defined by the Bible. The Bible is very clear that Christ was raised from the dead in bodily form. The empty tomb was described by all four Gospels. Paul makes it clear that if Christ was not raise from the dead our hope is in vain, we will not be resurrected:

1 Corinthians 15:3 For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, 4 that he was buried, that he was raised on the third day in accordance with the Scriptures, 5 and that he appeared to Cephas, then to the twelve. 6 Then he appeared to more than five hundred brothers at one time, most of whom are still alive, though some have fallen asleep. 7 Then he appeared to James, then to all the apostles. 8 Last of all, as to one untimely born, he appeared also to me. 9 For I am the least of the apostles, unworthy to be called an apostle, because I persecuted the church of God. 10 But by the grace of God I am what I am, and his grace toward me was not in vain. On the contrary, I worked harder than any of them, though it was not I, but the grace of God that is with me. 11 Whether then it was I or they, so we preach and so you believed. 12 Now if Christ is proclaimed as raised from the dead, how can some of you say that there is no resurrection of the dead? 13 But if there is no resurrection of the dead, then not even Christ has been raised. 14 And if Christ has not been raised, then our preaching is in vain and your faith is in vain. 15 We are even found to be misrepresenting God, because we testified about God that he raised Christ, whom he did not raise if it is true that the dead are not raised. 16 For if the dead are not raised, not even Christ has been raised. 17 And if Christ has not been raised, your faith is futile and you are still in your sins. 18 Then those also who have fallen asleep in Christ have perished. 19 If in this life only we have hoped in Christ, we are of all people most to be pitied. 20 But in fact Christ has been raised from the dead, the firstfruits of those who have fallen asleep. 21 For as by a man came death, by a man has come also the resurrection of the dead. 22 For as in Adam all die, so also in Christ shall all be made alive. 23 But each in his own order: Christ the firstfruits, then at his coming those who belong to Christ. 24 Then comes the end, when he delivers the kingdom to God the Father after destroying every rule and every authority and power. 25 For he must reign until he has put all his enemies under his feet. 26 The last enemy to be destroyed is death. 27 For “God has put all things in subjection under his feet.” But when it says, “all things are put in subjection,” it is plain that he is excepted who put all things in subjection under him. 28 When all things are subjected to him, then the Son himself will also be subjected to him who put all things in subjection under him, that God may be all in all.

Christ triumphed over sin and death, why would he have to die a second time, the Scripture is clear that he did not:

Romans 6:3 Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? 4 We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life. 5 For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. 6 We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. 7 For one who has died has been set free from sin. 8 Now if we have died with Christ, we believe that we will also live with him. 9 We know that Christ being raised from the dead will never die again; death no longer has dominion over him. 10 For the death he died he died to sin, once for all, but the life he lives he lives to God. 11 So you also must consider yourselves dead to sin and alive to God in Christ Jesus. 12 Let not sin therefore reign in your mortal bodies, to make you obey their passions.

Those who claim, like Crossan that this will not change their faith, don’t have a faith that’s based on the biblical record. Crossan doesn’t believe that the Bible is the word of God, he believes that Jesus existed and he believes in God but he believes that the Bible was written by men who had an agenda and it’s not historically accurate. Those like Crossan don’t believe in the supernatural aspects of the Bible. They don’t believe that Jesus was raised from the dead, so of course their faith isn’t going to be destroyed if this (by some stretch of the imagination) turns out to be true.
But biblical Christianity is based on the fact that Jesus lived a sinless life in perfect obedience to the will of God, died for the sins of his people, rose again from the dead (proving that God accepted his payment for the sins of his people), ascended into heaven and is seated on the right hand of God, the Father Almighty. We affirm this every week when we say in unison, the Apostle’s Creed:

I believe in God, the Father Almighty,
the Creator of heaven and earth,
and in Jesus Christ, His only Son, our Lord:

Who was conceived of the Holy Spirit,
born of the Virgin Mary,
suffered under Pontius Pilate,
was crucified, died, and was buried.

He descended into hell. [See Calvin]

The third day He arose again from the dead.

He ascended into heaven
and sits at the right hand of God the Father Almighty,
whence He shall come to judge the living and the dead.

I believe in the Holy Spirit, the holy *catholic church,
the communion of saints,
the forgiveness of sins,
the resurrection of the body,
and life everlasting.

Amen.

I have examined the claims made by the makers of this documentary and I am absolutely positive that they are false, not just because I believe that Jesus is the Son of God, who came to die for his people but because the evidence does not stand up to scrutiny.
Related posts:
Oh no! How will Christianity survive?
Update on the tomb of some guy named “Jesus”
The Tomb of “Jesus?”
Jesus, son of Joseph
“Jesus” tomb links