This great post reminded me of the great Reformed theologian, Francis Turretin, who wrote:

Although the sacraments are external means and instruments applying (on the part of God) the promise of grace and justification, this does not hinder faith from being called the internal instrument and means on the part of man for receiving this benefit offered in the word and sealed by the sacraments [16.7.20].

The question is not whether faith alone justifies to the exclusion either of the grace of God or the righteousness of Christ or the word and sacraments (by which the blessing of justification is presented and sealed to us on the part of God), which we maintain are necessarily required here; but only to the exclusion of every other virtue and habit on our part…. For all these as they are mutually subordinated in a different class of cause, consist with each other in the highest degree [16.8.5].