“Here I wish to affirm once more that religion can never justify intolerance or war. We cannot kill in God’s name!” (Benedict XVI, Verbum Domini, Post-Synodal Apostolic Exhortation, September 30, 2010, Part 3)
Desiring with an ardent desire to liberate the Holy Land from the hands of the ungodly, we decree with the advice of prudent men who are fully familiar with the circumstances of the times, and with the approval of the council, that all who have taken the cross and have decided to cross the sea, hold themselves so prepared that they may, on June 1 of the year after next (1217), come together in the Kingdom of Sicily, some at Brundusium and others at Messana, where, God willing, we [the Pope, Innocent III] will be present personally to order and to bestow on the Christian army the divine and Apostolic blessing.
Holy Land Decrees of the Fourth Council of the Lateran (source for translation)
Everybody knows that popes only extremely rarely exercise their alleged power of infallibility. And, of course, any time a contradiction between popes is noted, it is simply alleged that one or the other or both of the popes is not exercising his infallibility.
But my point is a little different. My point is that papal teachings are not generally trustworthy, because they contradict one another. Innocent III justifies the crusades on religious grounds. Benedict XVI says, in effect, that Innocent III (and the fourth Lateran council in general) was wrong.
How can you know who is right? The answer is that you’re going to have to exercise private judgment. You’re going to have to look to a source that’s more reliable than the Roman bishops. May I respectfully submit to you, dear reader, that the standard by which you should be judging the teachings of both Innocent III and Benedict XVI is Holy Scripture.