I came across in John H. Arnold's "A Very Short Introduction to History" on page 85 saying that "Practically all historians writing today are marxists (with a small 'm'" and that the reason for this is because most historians have inherited the view from Marxist methodology that "social and economic circumstances affect the ways in which people think about themselves, their lives, the world around them and thus move to action.".

How true is this? Are there many that realize this and subscribe to the above? What's the main differences between working with a Marxist methodology and a marxist methodology (with a lower-case m)? I'm not looking for a debate on politics, I'm just genuinely curious on how the inheritance from historical materialism affects historians today (if it does at all) and their methods - while at the same time not necessarily being a Marxist in a political sense.