I agree —
pistis (faith) in the biblical sense is not mere intellectual assent or profession; it’s living, active trust that manifests itself in obedience. The Reformers’ use of
“faith alone” was never meant to describe a
faith that is alone, but rather to affirm that nothing
in addition to faith (no works or merit of our own) contributes to justification.
James 2 helps clarify the distinction:
“Faith, if it hath not works, is dead, being alone.” (
James 2:17)“Ye see then how that by works a man is justified, and not by faith only.” (
James 2:24)This isn’t a contradiction of Paul’s teaching, but a complement to it — Paul addresses
how we are justified before God (by grace through faith, apart from works), while James addresses
what kind of faith justifies (
a living faith that inevitably produces obedience).
In that sense, I agree entirely that obedience is inseparable from genuine faith —
not as an added requirement
for salvation, but as the natural fruit
of it (
Ephesians 2:8–10;
Titus 2:11–14).
So yes,
pistis and obedience are indeed co-instantiated, as you put it — two sides of the same coin of saving belief. The difference is that “faith alone” guards the foundation (grace, not merit), while obedience and repentance demonstrate the reality of that faith.