“by faith alone”
Paul does not teach a “faith alone” position, as I have sometimes heard it put. Rather, his is a “by faith alone” position. This is not just a verbal quibble; the “by” is all-important here. The faith by which sinners are justified, as it unites them to Christ and so secures for them all the benefits of salvation there are in him, that faith perseveres to the end and in persevering is never alone. It is, as Luther is reported to have said, “a busy little thing.”
Richard Gaffin, By Faith, Not by Sight: Paul and the Order of Salvation (Paternoster, 2006), 105.