A quarter-century ago, on Dec. 25, 1991, as the last Soviet premier, Mikhail Gorbachev, resigned after a final attempt to keep the Communist state alive, I was so optimistic for the future. That year and the years leading up to that moment were a period when anything felt possible. The ideals of freedom and democracy seemed within the reach of the people of the Soviet Union.

I remember the December evening in 1988 when I was having dinner with friends and my mother in Paris. My family and I still lived in Baku, capital of...