George MacDonald never called himself a "universalist," nor promulgated a dogma of universal reconciliation.
But he believed that (as Scripture tells us) it was God's will that none be lost, and all saved, and that "the great and beautiful and perfect will of God must be done."
One of the arguments against universal reconciliation is that it requires God to involve the override of man's free will, to compel them to turn to Him.
A notable difference between C.S. Lewis and George MacDonald, for example, is reflected in Lewis' book The Great Divorce (notwithstanding that Lewis features MacDonald himself as his Tour Guide to Heaven!), where people are depicted as choosing damnation; the gates of hell are locked from the inside.
A contemporary theologian much influenced by Lewis is Jerry Walls, whose point of view on this topic was highlighted Four Views on Hell. The fundamental question, Walls affirms, is our understanding of God. “Do we really believe that God truly and deeply loves all persons and desires the salvation of all?”
If so, then “what damns a person is a decisive choice of evil…[which] depends on what I have called ‘optimal grace.’”
This is the idea that “God will do everything he can, short of overriding our freedom to communicate the gospel to us and elicit a positive response from each of us.” If an individual has rejected the gift of optimal grace, “that constitutes the decisive choice of evil that leads to eternal damnation.”
But would people ever freely choose not to be reconciled to God?
MacDonald could not believe it, as perhaps best illustrated in his Unspoken Sermon, The Last Farthing (see the May 19th to 27th entries in Consuming Fire). When God finally separates entirely from a man, and casts him into the outer darkness, the resulting misery is impossible to bear. In his classic book The Inescapable Love of God, philosopher Thomas Talbott argues that for man to not, in the end, choose to be reconciled to God is a logical impossibility, given Walls' compelling notion of 'optimal grace:'
"If MacDonald was right about this, as I believe he was, then God knows from the outset that,
beyond a certain limit, libertarian freedom cannot survive further separation from the divine nature. Accordingly, no matter how tenaciously some sinners might pursue a life apart from God and resist his living purpose for their lives, God has, as a sort of last resort, a sure-fire way of shattering the illusions that make their rebellion possible in the first place. To do so, he need only honor their own free choices and permit them to experience the very life they have confusedly chosen.
When, as a last resort, God allows a sinner to live without even an implicit experience of the divine nature, the resulting horror will at last shatter any illusion that some good is achievable apart from God; it will finally elicit, therefore, a cry for help of a kind that, however faint, is just what God needs in order to begin and eventually to complete the process of reconciliation."
George MacDonald, Universal Reconciliation, and Free Will: A Few Brief Thoughts — The Works of George MacDonald