Providing for the common defense is part of protecting individual liberty, a term which does not limit itself to protection from domestic threats. "Providing for the common good" is a much much broader concept than is contemplated by our Constitution.
Individual liberty can only be protected if the common defense is first provided for. The common defense is an aspect of the common good. The common defense and the common good are logically prior to the State's promotion of individual liberty.
"Providing for the common good" is a much much broader concept than is contemplated by our Constitution
So why is "the general welfare" mentioned in the Preamble?
Maybe you consider "the general Welfare" and socialism to be synonymous. They're not.