I meant "founder" in the sense that it was FDR who got the federal government into the "entitlement" business; but you are absolutely right, it was LBJ's "Great Society" agenda that created the Marxist fiasco we are burdened with today.
You would be surprised--I'd say 95% of conservatives believe FDR was the "Father of Liberalism". He certainly was not. He proposed and initiated some social programs, but he did not spend 65% of the budget on them like we are today.
LBJ is the TRUE father of Marxism.
Richard Nixon, George Herbert Walker Bush and George Bush have been the biggest increasers of Marxism since LBJ. Only Ronald Reagan reversed course since LBJ.