The concept 'free-will' can be considered as one model for how the human organism operates in its outer environment. But this doesn't show that free-will is not part of the causal framework in which the organism operates. A specific "act of free-will" is simply a model we use to describe what is still basically a causal physical response. It's the notion of free-will as something independent of all the physical processes that all physicalists are disputing, and in this sense I think autonomous-free-will can be described as an illusion, or at best as a conceptual model.
I say free-will is a 'model' of response because thinking in terms of models allows us to accept a level of abstract detachment. We regularly use models for systems - conceptual ideas that represent something on a manageable arbitrary level. We do this probably because we have to - it's how our brains manage external perceptions as patterns and memories, one of those perceptions being the self, another, free-will, being a model of how that self responds. It may be natural for the organism itself to feel that free-will is something the organism does actively and autonomously simply because of the proximity and complexity of how an act of free-will comes about.
If you accept causality and the level of physicalism that has been discussed here, then I don't see how free-will in its religious and autonomous senses has any meaning. And without free-will what is religion, other than one more conceptual abstraction of the physical environment of the organism. All religious ideas come to us through reading, listening and seeing - all part of physical environment acting on the organism as a whole, and through layers down to the brain; the brain that already has a history and hence existing interconnections and chemistry that is amenable to these inputs, or not. Even an internally occurring "sign", a revelation, can be explained as a religious event only in the context of pre-existing knowledge about religion.
For any individual, how does their brain respond to a religious idea (or any input)? As an excited, inhibited, or conditioned response (utilising yet another model of behaviour)? Probably in some complex combination. The emergent response to a religious idea may be whatever the organism's brain does internally, plus how that operates on the outer organism. So a theist response might be to offer a supportive argument. This particular organism (me) might respond with a criticism. The fact that the response may be complex does not detract from the fact that it came about from a complex interaction of components within the organism, albeit with externally sourced inputs, many of which have been consolidated over time. We call that a free-will response, using the free-will model. But that's all it is - it is a caused response (still assuming causality).
In this context the only difference between a person performing an act out of 'free-will' and one who has been induced into performing the act, say through hypnosis, is that the most influential and most recent causal events that preceded the act came from within the organism for the former, but from outside the organism for the latter.
One of the main objections to physicalist non-autonomous free-will comes about because it's difficult for some to accept this point of view - but this in itself is a response, to prior physical activity. When you "feel" free-will must be real, that feeling itself is merely a response with a physical base.
The next paragraph is long winded because I've gone out the way to put it in terms of a non-agent mechanical reaction. We're not used to doing this. It's possible our natural language that describes us as agents that interact is a convenience, and efficiency that has evolved naturally, just as we naturally and conveniently attribute agency and free will to inanimate objects sometimes.
Other objections are associated with justice and culpability. You might ask me, "How can you justify locking up that 'criminal' organism, when on your model he didn't 'willfully' carry out the crime?" My response would be, "Well, this organism's response is to do just that." All organisms tend to avoid self harm, and through evolved empathetic responses we generally try to avoid harm to others. That particular criminal organism caused harm, albeit indirectly and in a non-autonomous free-will caused sense, so the complex collective socially constructed response of this set of organisms, this social group, is to prevent further harm by locking up that criminal organism. The notion that this sequence of events might act as sufficient causal input to that criminal organism that in time it's caused actions might be to no longer cause harm to others, is also compatible. Similarly, the desire for retribution can be considered as another physical response. The complexity of these interactions is not evidence against physicalism.
A physicalist view of free-will as an illusion or a model does not entail the collapse of society and morality. It may even inform us better than some of the many arbitrary and conflicting reasonings of the various religions.