Augustine and free will
In the book “On the Free Choice of the Will” Augustine searches for an explanation for the evil in the world. This, for him, is a religious problem as in his view it is a god that created the world and since this god is purely good, there must be some other source of evil and wrong doing.
The first possible explanation lay in Manicheaism, which is a religion with as its major proposition that there exist two cosmic principles which make up the world. There is the good, spiritual force and the evil, material force. These two are in constant conflict, which explains the real conflicts which take place on earth between good and evil. In this theory there is room for evil next to an absolute good, however it eventually was not what Augustine was looking for. Manicheaism is seemingly incompatible with the christian sense of an almighty god as this entity should be able to dismiss of the evil force if it was truly almighty.
Augustine found a psychological answer to his question: free will. It was the ability to choose in human beings that caused them to occasionally do wrong and evil deeds. God created humans in this way, and let them choose between good and evil. This resulted in not actually god being responsible for the evil in the world, but the wrong choices of humans. Augustine then blamed people choosing wrongly for not adequately using their capacity to reason, but the idea remained that every choice is essentially a free one.
However, with the embers of the debate on free will still blazing, there are many reasons to believe that choices are not entirely free. One example is social determinism, namely the influence of the people around an individual on their choice. Another, more extreme, is general causal determinism. This implies that everything that will ever happen is already determined and so choices are not really choices, but rather consequences of earlier events.
It is important to keep in mind that these objections are not all in line with the christian idea of a divine power. Another question to consider within this tradition is why Augustine thought it better that humans would have free will and proceed to often do wrong things, than humans always doing the right thing by default (as his god would have designed humans in the best way).