As an ordained priest in the Catholic Church at age 25, he served for the next 10 years. By 1545 Knox fell under the powerful influence of George Wishart, who was Scotland's "morning star" of Reformation. Wishart, being burnt at the stake in St. Andrew's, would forever mark the turning point in spiritual life of Knox. He renounced Catholicism, and openly professed the Protestant faith.
Through a tragic turn of events, Knox was taken captive, and spent 19 months in the galleries of a French ship. After his release, he continued pastoring in England and Geneva, where he encountered John Calvin.
In 1559, Knox was called back to fulfill the preaching at Edinburgh's historic St. Giles Cathedral. His house can still be seen today, located on the Royal Mile, yards from Edinburgh Castle. While ministering in Edinburgh, the great controversy between Knox, and Mary, Queen of Scots arised. Mary, a devoted Catholic with French sympathies, and Knox, a resolute Protestant with Scottish self-determination was sure to produce many sparks! The struggle is legendary, similar to another John and a wicked ruler who insisted on having his brothers wife! The only difference, Mary lost her head, instead of John!
Besides the great preaching and leadership of Scotland's Reformation, Knox produced two important articles, whick served to form the policy and future government of Scotland. 1) The First Book of Discipline and 2) The Book of Common Order