No slogan encapsulates biblical Reformation theology as well as the one drawn from this verse. It is justification by faith apart from works and if apart from works, then the justification of the sinner is by faith alone, sola fide.
Get a grip on the reality of your redeemed life, Paul says, your miserable attitude and anxiety bespeaks of unfaithful unbelief. Knock it off! Time for an attitude adjustment. Rejoice, again I say rejoice!