Basic Beliefs of Christianity: Sola Fide

Martin Luther said that on this doctrine "the church stands or falls". Clearly he thought it was important. But are Christians really saved by faith alone? The words faith alone only appear once and they might surprise you:

"You see that a person is justified by what he does and not by faith alone." (James 2:24)


So how could the reformers say that Christians are saved by faith alone?