Faith causes action, it is not alone.
I agree; faith is not alone. And that is the reformed and Lutheran perspective as well. I think where we’re butting heads is in what the reformers referred to as the confounding of justification and sanctification. The former is seen as “a legal act of God’s free grace whereby He pardons our sins and accepts us as righteous in His sight, but does not change us inwardly”; the latter is “a moral or re-creative work, changing the inner nature of man.”
As Berkhof goes on to say, “while they made a careful distinction between the two, they also stressed their inseparable connection. While deeply convinced that man is justified by faith alone, they also understood that the faith which justifies is not alone. Justification is at once followed by sanctification, since God sends out the Spirit of His Son into the hearts of His own as soon as they are justiied, and that Spirit is the Spirit of sanctification.”
The Solid Declaration of the Formula of Concord makes the same point:
. . . neither renewal, sanctification, virtues nor good works are tamquam forma aut pars aut causa iustificationis, that is, our righteousness before God, nor are they to be constituted and set up as a part or cause of our righteousness, or otherwise under any pretext, title, or name whatever to be mingled in the article of justification as necessary and belonging thereto; but that the righteousness of faith consists alone in the forgiveness of sins out of pure grace, for the sake of Christ’s merit alone; which blessings are offered us in the promise of the Gospel, and are received, accepted, applied, and appropriated by faith alone. . .
For good works do not precede faith, neither does sanctification precede justification. But first faith is kindled in us in conversion by the Holy Ghost from the hearing of the Gospel. This lays hold of God’s grace in Christ, by which the person is justified. Then, when the person is justified, he is also renewed and sanctified by the Holy Ghost, from which renewal and sanctification the fruits of good works then follow. . .
This should not be understood as though justification and renewal were sundered from one another in such a manner that a genuine faith sometimes could exist and continue for a time together with a wicked intention, but hereby only the order [of causes and effects, of antecedents and consequents] is indicated, how one precedes or succeeds the other. For what Luther has correctly said remains true nevertheless: Faith and good works well agree and fit together [are inseparably connected]; but it is faith alone, without works, which lays hold of the blessing; and yet it is never and at no time alone.
bookofconcord.org/sd-righteousness.php (paragraphs 39-41)
And there is a short treatment of James 2 in paragraph 42:
Many disputations also are usefully and well explained by means of this true distinction, of which the Apology treats in reference to the passage James 2:20. For when we speak of faith, how it justifies, the doctrine of St. Paul is that faith alone, without works, justifies, Rom. 3:28, inasmuch as it applies and appropriates to us the merit of Christ, as has been said. But if the question is, wherein and whereby a Christian can perceive and distinguish, either in himself or in others, a true living faith from a feigned and dead faith, (since many idle, secure Christians imagine for themselves a delusion in place of faith, while they nevertheless have no true faith,) the Apology gives this answer: James calls that dead faith where good works and fruits of the Spirit of every kind do not follow. And to this effect the Latin edition of the Apology says: Iacobus recte negat, nos tali fide iustificari, quae est sine operibus, hoc est, quae mortua est. That is: St. James teaches correctly when he denies that we are justified by such a faith as is without works, which is dead faith.