I might have skimmed a few of the posts in this thread - and don’t think I’ve read very many in much depth - so my answer here may repeat a lot of stuff they may have already been said. And this is me writing with my own hat on (not as a moderator, but as just another participant here - hopefully my words will be weighed for their own merits alone. In other words - this is not put forward as any sort of ‘Biologos’ opinion, but only my own.
To the extent that anybody worships a “Creator” of everything and everyone, then they are worshipping the same (with respect to the worshipped being ‘Creator’) - no matter what different word they may have for such a being, and whether they do so from within a Christian tradition or not. To the extent that anybody worships an “ultimate Good”, then I would say their worshipped being also is yet another Christian understanding of God - and so then … the same, no matter what words or tradition their worship is embodied in.
To the extent that anybody attributes false attributes to God (I would say, making God out to be an evil tyrant or a deceiver, for example), I say that to the extent they do that, they are worshipping something that is not the Christian understanding of God (whether they do so from within a Christian tradition or not).
Furthermore, I think it necessary to concede (as has been said before), that none of us can have a complete understanding of all of God. We will have necessarily incomplete understandings, and certainly some wrong understandings too. So all of us, then are giving imperfect worship to God, probably some a lot more than others. The being we hope to have a relationship with is a forgiving one, if the Christian and the biblical narrative are true as many of us here see it. So thankfully we don’t all have to ace any “factuality” exams before God will relate to us. I think Christ is our true picture of God, but he doesn’t guarantee us that our understandings suddenly then become infallible.
In short, I think there are Muslims who (by evidence of their lives) worship the true God, and Muslims who worship false gods. I think there are Christians who worship the true God, and Christians who worship false gods. (and I think people, sinful as we are, can fluidly move between those categories as we variously resist or fall to temptations in our lives.) And since people will accuse me here then of suggesting that there are “many equal paths” to God and that all religions must therefore be right, I will pre-emptively correct them with this: I believe Christ, and Christ alone is our hope, no matter what religion we call ourselves. Whether or not people have uttered some set of “right words” in the “right language” addressing Christ by the “right name” is of no consequence. If Christ has not got hold of their heart, no right words or doctrines have saved them. Whether Christ has got a hold of a person’s heart - that is everything. If he has got hold of their heart, no lack of doctrines or lack of using familiar names or recognized religious language can hurt them, or stick with them for long - as Christ will teach them everything they need when they need it.