Answer:
Martin Luther's efforts to reform the theology and practices of the Catholic church resulted in the Protestant Reformation, in which Protestants separated from the church.
Lutheranism is a theological movement to reform Christianity with the teaching of justification by grace through faith alone (which went against the Roman view of "faith formed by love", or "faith and works".) Lutherans believe that humans are saved from their sins by God's grace alone, through faith alone.
Also note that Lutherans do not follow the catholic Pope, and they do not need to confess their sins through an intermediary (such as a catholic priest). They can pray directly to God.