From An Atheist Named Swinburne:

More importantly, Swinburne rejects the existence of God, where God is conceived of as being omniscient in the sense that ‘God knows everything that has ever happened and that ever will happen’. Many people, including many Christian believers, believe in such a God. But Swinburne asserts that these many devout Christian believers are mistaken, and that there is no such being.

God is a perfectly free person, according to Swinburne, and a perfectly free person cannot know with certainty what actions he/she will choose to do in the future (COT, p. 177). Perfect knowledge of the future is logically incompatible with perfect freedom; therefore, it is logically impossible for God to both be perfectly free and for God to also have perfect knowledge of the future.

God must either be perfectly free and have imperfect knowledge of the future, or else God has perfect knowledge of the future and does NOT have perfect freedom. Thus, Christians who believe in a God who is both perfectly free and who has perfect knowledge of the future believe in a God who not only does not exist, but they believe in a God who cannot possibly exist, because they believe in the existence of a being with attributes that are logically contradictory.