The terms ‘materialism’ and ‘materialist’ seem to be popularly misunderstood. As such, it bears mentioning that there are two wildly different interpretations of what these terms mean.
Perhaps the more common interpretation is based around a desire for material possessions. In this view, a ‘materialist’ is someone who continually wants to own more things.
A much more interesting definition holds that being a ‘materialist’ means that you believe everything in the universe is made of comprehensible materials, interacting with each other on the basis of laws we can understand. This viewpoint definitely raises important questions in philosophy – and potentially lethal ones in theology – it is also much more worthy of consideration than the fact that neighbour X might want a bigger car than neighbour Y.