The class war is the basis of socialist politics. The Hallmark.
The Labour Party has always shied from accusations of class warfare, aiming to speak for the whole community. Socialists contend, though, that where the community is divided by class it cannot be treated as a whole. Inevitably, government policies will benefit one side or another in the struggle between the tiny minority who own the wealth of society, and the vast majority who only own their ability to work.
When we talk of class warfare, we are not talking about rioting in the streets, attacking middle class people or anything of the sort, but the continual day to day struggle to secure access to the mneans of living for millions of people.
So far as we are concerned, there is no middle class, no separate privilleged mid-layer between the workers and the capitalists, only a vast army on different pay scales being exploited by the same bunch of owners.
Once we accept this, we cannot conscience co-operation with parties that advocate policies to the betterment of the ruling class. We are hostile to them - Labour, Liberals, Tories - and seek to frustrate their ends by building a socialist movement to abolish the system they prop up. Workers run society from top to bottom, it's time they ran it in their own interest...