Yes, I often see this assertion. But I also often see people that make this assertion are unable to give a proper understanding of the concept of God or at least THEIR OWN informed view of it.
The problem with the word 'God' isn't so much that it doesn't have any meaning. It's that 'God' has too wide a range of meanings.
There's the polytheism/monotheism question.
Leaving that aside for the purposes of his thread and just restricting our attention to monotheism, there's the mythical Yahweh of the Biblical Old Testament and the mythical Allah of the Quran. There's the Vishnu and Siva from Hindu theistic mythology. There's Advaita's impersonal Brahman and Neoplatonism's ineffable One.
All of these are supposed to be the single, unique, one-and-only divine principle. So what's the relationship between all of the very divergent names and stories?
Is only one of them supposed to be real and true? If so, how can we know which one? Or are they all supposed to be true, just different mythical personas worn by a single ineffable power? Theists disagree, often violently, about those questions.
How does this hypothetical One God manifest in human history? How does God reveal "him"-self to human beings like us? How can finite human human beings, from their end and given all of their limitations, ever be sure that they have been touched by a God? How can we distinguish between true revelations and false delusions?
Must this God be omni-everything? Omnipotent, omniscient, omnibenevolent?
Must this hypothetical divine power be a person like we are? Most theistic religions seem to insist very strongly on that element of their myths. But how could we know that? And given all the divine attributes that tradition tries to load onto the God concept, how is human-style personality even possible? What about all the problems that arise from trying to imagine a "person" who is absolutely unique, one of a kind, and alone? Can personality even exist outside a social context? Would emotions like love have any purpose or meaning to a One without a second? What about the conceptual problems that arise from trying to imagine a "person" that conforms to all the omnis in logically consistent fashion while "living" outside time entirely? How could a timeless being react to temporal events or discover anything new?
Or is God a set of abstract philosophical functions? Is God whatever the first-cause of the universe's flow of causation might be? The foundation of being itself? The universe's hypothetical designer? The goal towards which everything supposedly proceeds and evolves? Even if all of these philosophical functions make sense, which isn't clear, how can we be sure that there's one single being that ties them all together and somehow embodies all of them? And what, in turn, connects and identifies all of these philosophical functions to the tales of the personal deities from the historical religious myths?
Classical theists of course see reality just as the evidence for obvious reasons. For them it is not a question of "evidence", they accept reality as it is including all the empirical discoveries.
Of course simply by definition, a classical theist is already embedded in his or her religio-mythical context. He or she is already a Christian, Jew, Hindu, Sikh or Muslim and has already embraced most of the presuppositions that are native to his or her version of one of those traditions.
Agnostics like myself don't just absorb a religious tradition through an accident of birth or whatever, and then commence our thinking from within that context of a-priori faith. So, as a result, a whole galaxy of questions about this 'God' concept present themselves to us that Christians, Muslims or whatever will typically just shrug off and ignore. They already have their God concept, as far as they are concerned the only true and legitimate one, the one that's native to their own strand of tradition.