Introduction To Christianity - pg. 202

Accordingly, from the point of view of the Christian faith,
man comes in the profoundest sense to himself not through
what he does but through what he accepts. He must wait for
the gift of love, and love can only be received as a gift. It
cannot be "made" on one's own, without anyone else; one
must wait for it, let it be given to one. And one cannot become
wholly man in any other way than by being loved,
by letting oneself be loved. That love represents simultaneously
both man's highest possibility and his deepest need, and that
this most necessary thing is at the same time the freest and
the most unenforceable, means precisely, means precisely that
for his "salvation" man is meant to rely on receiving. If he
declines to let himself be presented with the gift, then he
destroys himself. Activity that makes itself into an absolute,
that aims at achieving humanity by its own efforts alone,
is in contradiction with man's being.