God has all planned out so the earth will be enough for all. The over population is only a myth, as you see countries who originally pushing it (i.e. China etc) has recently reversed the policy, as aging population destroys economic growth (i.e. Japan and part of EU).
Some scientist projected world will run out of food by now early on, but that never happened, God always reveal new ways we can supply ourselves, so the food supply didn't dry up, it increased so much that food is not the most important thing in most of the world any more.
HOWEVER, human sin is definitely an issue, as you see bad policies destroy countries (i.e. see North Korea, Venezuela). This always happen when people think they are smarter than others (and ignores God). A really good example is China, half a century ago they take the US liberal idea that over population is the root of poverty, and now they found out if you just free up the policy, the more people you have, the better, I heard they have totally abandon the one child policy, and did 180 degree turn, now rewarding for extra kid