Most Buddhists I know have gone though or are going through the "all is one" and "All religions are the same" and "we're saying the same thing just with different language," thing. I know I did, and I remember my initial disappointment when I started to realize that this was not the case at all in Buddhism. Some people still have a bit of the "fear of god" in them, so they like to keep one foot in Buddhism while keeping the other in some kind of theism. It's like an ambivelant Pascal's wager.
Actually what I pretty much believe now is that "All religions except Buddhism are pretty much the same." Most are some variation on the "all is one" or "let's all be god" themes. Buddhism is the *only* one that teaches that all of these views are still self views.
I think a lot of western Buddhists don't feel it is appropriate to really commit to one religion and dismiss the others as ultimately false because that would make them come across as too religious
and summon images of bible thumpers, which is often what they are rejecting when they seek out Buddhism.
Also, if you say you think other religions are ultimately false and misleading, then you'll probably come across as intolerant of others' religions, which is taboo in society and frowned upon.
That being said, however, the greater thinkers of Buddhism and Shakyamuni himself all readily laid the hammer down and declared that the teachings of externalists were false and did not lead to liberation. They might indeed lead one to heavenly rebirth, but that is still samsaric and ultimately misleading and incapable of allowing for liberation.
Basically, anything that is not in line with the teaching of the Tathagata is merely palliative and not curative. The only secure refuge is the Triple Gem because worldly gods and spirits, including Brahma, are like us trapped in samsara.
In English material this kind of thought doesn't seem to appear too much, but recently I've read Master Sheng Yen and Master Yinshun who both say the same thing: refuge in worldly gods is misleading and the only secure refuge is the Triple Gem. They don't sugar coat anything, so to speak.