why doesnt he save them all
because it interferes with free will
but we really knew that since about Form 1 days innit
God's knowledge of the past and future exercised Thomas Aquinas 1280 or thereabouts, and this is involves creating people whom he knows will not be saved....
which brings us nicely to - - - predestination.
now....( on a diversion)
Archbishop Laud (*) 1620 or thereabouts, was thought to be an arminian heretic - and the failure to introduce Laudian reforms norrrrrrrth of the border led to the rather bare surroundings of St Giles Cathedral where the late Queen lay ( no bishops and a cathedral, yeah even the fluffy beebsters pointed that one out)
and the Arminian heresy is here:
https://en.wikipedia.org/wiki/Arminianism
and if after reading that, you have any interest in predestination you are a better man than me