He had much influence on the 12th century politics of church and state. For example:
- In 1128 he wrote the Rule for the Knights Templar, the defenders of the Holy Land. One rule said a man could not join until he was 21. This is where, for over 800 years, the "21st birthday" celebration came from.
- In 1130 two Popes were elected. Bernard was asked to decide who was the real Pope - Innocent II or Anacletus II. He gave clear reasons for supporting Innocent, and most of Europe accepted this, though it took eight years of campaigning by Bernard to end the schism.
- In 1145 his former pupil became Pope Eugenius III. Bernard wrote him a book of guidance, stressing the role of Pope as a spiritual leader rather than any kind of worldly prince. Bernard played a major part in Church Councils.
- In 1146 he preached all round Europe in favour of the Second Crusade to the Holy Land "since the Saviour is one again suffering in the place where he died for us". He was unjustly attacked for its failure.
- In 1148 Bernard defended Jews in the Rhineland from massacre: ".... they are the same flesh and bone as the Messiah. If you injure them, you will wound the Lord himself, for they are the apple of his eye".