Christians - why does believing in evolution make you an atheist or a devil worshiper?

When people talk about evolution - it is automatically umed that you do not believe in God or it is a debate between those who believe in God and those who do not. But Darwin himself believed in God - Here is a statement from Darwin: "Might not evolution itself be viewed as an instrument by which God has brought about, and is bringing about, his purpose for the cosmos?" F.R. Tennant took this further. So why does one get accused of being non spiritual when they believe in evolution?