The Meaninglessness of External Causes

Some philosophers say that our life is meaningless because it has a prescribed end. This is a strange assertion: is a movie rendered meaningless because of its finiteness? Some things acquire a meaning precisely because they are finite: consider academic studies, for instance. It would seem that meaningfulness does not depend upon matters temporary.
We all share the belief that we derive meaning from external sources. Something bigger than us - and outside us - bestows meaning upon our lives: God, the State, a social institution, an historical cause.
Yet, this belief is misplaced and mista…