Martin Luther was wrong! It is perfectly easy to distinguish faith from the works associated with faith.
In the absence of other translators rendering the text in question as “exercising faith” as opposed to “believe,” I conclude that in this instance the JW org have doctored the translation to suit their own interests. It thereby becomes a snub to the “just believe in Jesus” movements. JWs very much want to tell you that they have the works to show that they are doing a worldwide preaching work.
The whole of the Bible was written before the Enlightenment. That meant that the holders of power used any text or provocation, deceit or privilege to keep down the powerless. The motivation for enlightenment values was driven by the urge to destroy corrupt authority by the monarchy and Church. In a sense the western world woke up although it has taken a century or two to realize the application of Enlightenment ideals.
My point is that Bible values are not congruent with modern ethics. The notion of believing as far as the scriptures are concerned, is the primitive tribal one of loyalty to a group with which one can identify. In the same way that loyalty, before the coming of the nation state, was to one's tribal lord. You supported him and he defended you from your enemies. You "believed" in your lord. This was the familiar basis to the Biblical application of belief and faith, the religious notion being drawn from the tribal politics of the masses from countless past generations.
So “belief” was and remains a religious marker or token for both loyalty and personal identity within any religious community. Religious “belief” like tribal loyalty was a matter of pride, it was not supported by reason or evidence, more by a factor of human geography.
Beliefs were for primitives,"knowledge" is the infinitely better modern approach for the benefit of all.