The Reagan speech that has snippets in the video Q linked is titled "A Time for Choosing" and is known as "The Speech."
https://www.americanrhetoric.com/speeches/ronaldreaganatimeforchoosing.htm
It contains several key concepts, references, and phrases including
Christ's sacrifice, stopping the Nazis, 'the shot heard round the world', whether life is worth dying for, accommodation & appeasement = surrender & slavery, 'the road to war' vs 'the road to peace', 'the best hope of man' vs 'a thousand years of darkness', and "what we know in our hearts is morally right."
I especially like this:
"There's something going on in time and space,
and beyond time and space,
which, whether we like it or not, spells duty.
You and I have a rendezvous with destiny."