If I were a guest speaker in a synagogue, I wouldn't quote the New Testament either. Nor would I open up a big bottle of Valu-Rite Vodka in a Baptist church even though I don't share their views on alcohol. It's called common courtesy.
Paul wrote clearly about a similar situation in 1 Cor. 10:14-32. "All things are lawful but not all things are helpful." Verse 32 says "Give no offense to Jews or to Greeks or to the church of God...." Why slam Rick Warren when he was clearly adhering to the teachings of the Bible?
The Apostle Paul was constantly offending Jews with Gospel of Jesus Christ. It is the reason that he was beaten; the reason that Jews rioted; and the reason Paul was arrested, imprisoned and finally martyred.
Read the book of Acts. Paul used to go into the synagogues to reason with the Jews from Scripture and to prove that Jesus was the Messiah. You will find that the Jews were offended. The Gospel offends. It is a stumbling block.
Where the Apostle Paul went into synagogues, boldly and unapologetically, with the purpose of sharing the Good News of the Gospel of Jesus Christ...
Warren went into the synagogue with the expressed purpose of teaching the Jews how to grow their Christless synagogues and compromised, apologizing for the slipped mention of a New Testament reference, by failing to give the Good News of Jesus Christ to lost hell bound people.
It is outright foolish to say that Warren was adhering to the teachings of the Bible, here.