Atheists worship materialism
The notions of atheism and materialism are two different concepts, and are not by design mutually inclusive ideas that stand hand in hand as an indistinguishable ideological position. Just because you are an atheist it does not mean you are materialistic; this statement is as correct a stance as saying that because you a theist it does not mean you are materialistic.
To fully understand whether or not "atheists worship materialism" the terms of this statement need to be defined, which are 'atheists', 'worship' and 'materialism'. In its broadest sense, an 'atheist' is a person who lacks belief in any form of Deity; 'worship' as a noun is defined as the feeling or expression of reverence for a deity, and as a verb means showing reverence and adoration for (a deity) or to honour with religious rights; and 'materialism' can either be defined as 1.) a tendency to consider material possessions and physical comfort as more important than spiritual values, 2a) the doctrine that noting exists except matter and its movements and modifications or 2b) the doctrine that consciousness and will are wholly due to material agency (Dialectical Materialism).
Using these definitions, the concept of whether or not 'atheists worship materialism' is very complex as the notions of 'atheism', 'worship' and 'materialism' on their own merits are multifaceted issues, as each term changes meaning depending on what context you use it in, such as whether or not you use the term 'materialism' in a capitalist or scientific sense. Atheists are not necessarily capitalist or scientific in their ideological stance, just as theists are not necessarily capitalist or scientific in their ideological stance, and consequently to assert that 'atheists worship materialism' is a misguided claim.