Daniel was one of a group of children taken from their homes in Jerusalem when King Nebuchadnezzar and the Babylonians invaded. These children were taken because they seemed to be bright, well-mannered, well-educated, and wise (Daniel 1:4). Daniel grew up in this foreign land holding onto the truths that he was taught as a young boy in Jerusalem.
Even as a young man Daniel took a stand for what he believed was right when he refused to eat food that was not permitted by the law of God (Daniel 1:5-16). Daniel grew in wisdom as demonstrated throughout the book of Daniel. He also gained great favor with the leadership of his adopted country. Through changes of leadership, Daniel was consistently chosen as a wise leader and was depended upon to give direction to the country. When Daniel was an old man he became friends with King Darius. But not everyone loved Daniel. Some men wanted his position. They convinced the king to sign a law that they knew would trap Daniel. The law stated that no man could pray to, or ask help from any king or deity for 30 days. For boldly praying to God, Daniel was cast into a pit of lions. King Darius declared Daniel’s God to be the true God when Daniel emerged safely from the den of lions.
Daniel consistently showed the people who surrounded him that there was only one true God.

by: http://www.whatchristianswanttoknow.com/missionaries-in-the-bible-10-to-emulate/#ixzz3kilnFj5s