Father Rutler told Hitchens, “you will either die a Catholic or a mad man.” And he told him that his lack of belief in heaven was the cause of his drinking. The Holy Spirit might yet reach Christopher.
Why? Because on a purely materialistic level, there can be no convincing argument that human embryos, who look somewhat similar to shrimp, shouldn't be marinated in Italian dressing, sauteed, and served on lettuce as an appetizer.
On a materialistic level, the easily accessible proof that embryos are "human" can be met with the all-purpose answer, "So what?"
On a materialistic level, nothing governs your thoughts and actions except the relentless and inescapable forces of heredity and environment, both of which were set in motion by the physical properties present at the beginning of the universe.
So for atheists, even polemical ones like Hitchens, it would make no sense to use words like "you ought to change your opinion because..." For them, there is no "because," except the absolutely irresistable cause-and-effect chains set in motion in the Expansion Phase governed by the Cosmoloical Constant, in the milliseconds after the beginning of Time, Space, Matter, and Energy.
One more point: If I had to be fetterd by manacles to someone at the Final Judgment, so as to share their eternal deserts, I would rather be shackled to an prolife atheist who was inexplicably loyal to the unborn child, than to a pro-abort Catholic who claimed loyalty to God.