The general meaning of the context?

Confused by the whole meaning the context. Does it tell us that the argument (from improbability) supports God's existence in the eyes of believers, while the same argument just proves the non-existence in non-believers' eyes?

Context:

The argument from improbability is the big one. In the traditional
guise of the argument from design, it is easily today's most popular
argument offered in favour of the existence of God and it is seen,
by an amazingly large number of theists, as completely and utterly
convincing. It is indeed a very strong and, I suspect, unanswerable
argument - but in precisely the opposite direction from the theist's
intention. The argument from improbability, properly deployed,
comes close to proving that God does not exist. My name for the
statistical demonstration that God almost certainly does not exist is
the Ultimate Boeing 747 gambit.