There are really two key contributions that the reader should appreciate for their historical influence, and one of them is way easier to stomach than the other. The first contribution is that Abelard helped to push the Catholic church away from illogical points of view. In both the Islamic world and the Latin world, Plato and Aristotle had been lost for hundreds of years, and then were reintroduced, so Abelard's opinion of those works helped to guide the Christian church in the direction of reasoned faith, instead of faith without reason.
By reading Aristotle's books on syllogistic logic, reason, and art, Abelard discovered for himself that Aristotle's works are genius, intuitive, and trust-worthy. He offers praise for Aristotle's works, and he argues that Christianity is the religion of truth, logic, and order; therefore, the works of Aristotle are compatible with the faith. He especially appreciates Nicomachean Ethics and he offers his own arguments about human intent. Essentially he says that a person should be held accountable for what they do and for why the do it. By analyzing a person's motives, a more clear picture of their ethical justice can be attained.
That logical opinion is what makes Abelard's second contribution so confusing. Abelard's Theological Works includes an argument for what happens to babies who die without their infant baptism. This was a key theological issue in the Catholic church that was threatening to split the church, but Abelard's argument helped to bridge that divide, and it remained the default answer for this question for hundreds of years. He said that babies who were not baptized were not eligible for heaven or to meet God. However, perhaps they do not go to hell, but instead to some intermediary holding place, like Limbo. This idea became called the Baby Limbo argument. One wonders what Aristotle himself might have said to such an argument.
