Shattering the Silence
When More and Rich have their final showdown in the courtroom, we get to see how both characters have changed (or haven't changed). Rich has become the power-grubbing, conniving villain that he was only flirting with at the movie's beginning—he betrays More, telling the lie that seals his death sentence.
On the other hand, More's principles have never shifted—he's never become willing to sell his soul to gain the whole world… or to gain Wales, as More acidly notes of Rich (who became Attorney General of Wales in exchange for lying about More).
The only change we see with More is his willingness to break his silence. He's avoided attacking the king's oath or Parliament's break with the Church, remaining quiet in order to save his life (while still refusing to sign the oath). But this tactic ultimately fails.
Now that he's sentenced to die, he opens his mouth and batters Parliament's break with the Church, before saying that they condemned him to death not for defying the king's supremacy but for refusing to approve of his unlawful marriage:
MORE: I am the King's true subject... and I pray for him and all the realm. I do none harm. I say none harm. I think none harm. And if this be not enough to keep a man alive... then in good faith, I long not to live. Nevertheless... it is not for the supremacy that you have sought my blood... but because I would not bend to the marriage!
A Pleasant Execution
More only remains silent when he needs to try—also on principle—to preserve his life (to pursue martyrdom without looking for a legitimate way of preserving one's life would be a kind of suicide).
But he's finally allowed to speak his mind and take a reverberating, verbal stand. It's a physical defeat, but a moral victory. He's come through with his identity intact.
So, it's all out in the open—More's path has delivered him at last to death. But the site of the execution outside the Tower of London is oddly peaceful, natural, and beautiful. When a priest who is present asks More if he's certain that he's going to God after death, More says: "He will not refuse one who was so blithe to go to him."
Then the executioner cuts his head off, before a final voiceover explains how most of More's persecutors were also executed (like Cromwell and the Archbishop of Canterbury), although Richard Rich managed to die in his bed.