What is luther's doctrine of salvation. what were the three changes he initiated to break away from the catholic church

Luther's doctrine of salvation:

Luther proclaimed salvation as a gift of God's grace, rather than something earned by human efforts.  The Roman Catholic Church spoke of God's grace also, but as an enabling power that helped human beings do the works required for obtaining salvation.  Luther still preached that we should do good works, but said those works were a fruit of being saved rather than a source of salvation. Luther had gone through his own personal struggle as a monk, feeling he was always under the judgment of God.  But then he came to realize, from Romans 1:16-17, that "in the gospel the righteousness of God is revealed" that gives salvation apart from human works.  This personal experience became the focus of his theology -- salvation as the free gift of God that lifts sinners from despair.

Changes initiated by Luther in breaking away from the Catholic Church:

Salvation by grace alone through faith (as noted above), rather than a combination of faith and works.Authority and truth found in Scripture alone -- not a combination of Scripture and church authorities and traditions (as Rome taught).Valuing lay people along with clergy as God's servants, rather than placing higher value on clergy.  This included ending monasticism (monks and nuns) as a way of life separate from society.Allowing marriage for members of the clergy (rather than the celibacy insisted on by Roman Catholic authorities for clergy).

There were other changes, but those were several.