The Flux Capacitor and the Summa…

Is It a Sin to Time Travel and Change History?

In 1985, we were introduced to Marty McFly and his adventures with Doc Brown. Through three movies we were confronted with the ethics of time travel and the goods and hazards that could come of it. So, we ask, what if you could travel back in time and change the past? What if you could undo a war, prevent a tragedy, or even stop Adam and Eve from sinning in the Garden? These questions, while fictional, spark real theological reflection.

If time travel were possible, would it be sinful to use it to change history? As Catholics, we must begin by grounding ourselves in what the Church teaches about God, time, and human freedom.

First, we believe that God is outside of time. As St. Thomas Aquinas says, God sees all things—past, present, and future—in one eternal moment (Summa Theologiae I, q.14, a.13). To God, history isn’t a line that unfolds gradually—it is a complete and perfectly known whole. This means that nothing in history escapes God’s providence, even the painful or tragic parts.

Now imagine someone traveling back in time to “fix” something they believe went wrong—perhaps to prevent a death, stop a betrayal, or end a war. The intention might even seem good. But the act itself risks a great spiritual danger: the assumption that we know better than God.

Pride is at the root of many sins, and time travel, if used to rewrite history, can quickly become a form of practical atheism—as if God’s providence were flawed or His plan lacked foresight. Pope Pius X, in Pascendi Dominici Gregis, warned that modern man often places human reason above divine revelation, seeking to redefine truth and history on his own terms. A man who uses time travel to control or undo God's plan might be guilty of this very sin—a refusal to trust the wisdom of divine providence.

But there’s another issue: free will. The Catechism teaches that man has been created with freedom and moral responsibility (CCC 1730). If someone were to go back and change another person’s decision—especially to erase or override it—they would undermine the dignity of human choice. No one, not even a time traveler, has the right to unmake someone else’s freedom before God.

And what about changing the Fall of Adam and Eve? Surely that would be a good thing—right? Surprisingly, the Church says otherwise. The Felix Culpa—the “happy fault” of Adam—is celebrated in the Easter Vigil liturgy, because through that fall, we received Christ our Redeemer. Aquinas explains that God permits evil to bring about a greater good (ST I, q.2, a.3). Without the Fall, there would be no Cross. Without sin, there would be no Incarnation. Trying to erase the Fall would also erase the Redemption.

So, is it a sin to time travel and change history? In principle, yes—if done out of pride, to deny God’s plan, or to manipulate others’ freedom, it would be morally wrong. Even if the intentions are good, the danger of overstepping our place as creatures and trying to play God is always present.

But if time travel were possible and used not to change the past, but to better understand it, to learn humility, or to witness God’s hand in history, perhaps it could be used virtuously—with great caution and reverence.

Ultimately, we are not called to relive the past, but to be faithful in the present. “Sufficient for the day is its own trouble” (Matthew 6:34). God does not ask us to control time. He asks us to trust Him. And that’s more powerful than any flux capacitor or time machine.