Twenty years ago, the wall that separated east and west Berlin came down, foreseeing the demise of Communist regimes throughout Europe.

For some, the wall's collapse marked the end of a murderous and oppressive era. For others, it provided an unprecedented opportunity for advancing the gospel.

It began with a challenge from a determined American president.

"Mr. Gorbachev, tear down this wall!" former President Ronald Reagan proclaimed.

Two years later on Nov. 9, east Germans scaled the Berlin Wall. That was the beginning of the end of the Cold War and Soviet Communism.

There were tears of joy, cheers and applause as east Germans poured through the opening into west Berlin. Some had been separated from friends and relatives for more than 25 years. Others had never set foot in the west.

The wall was built in August 1961 on the orders of Soviet Premier Nikita Kruschev. Over a period of nearly three decades, as many as 200 people had been killed attempting to escape to the west.

CBN founder Pat Robertson shared his reflections on the 20th anniversary.

He said he wasn't surprised when the wall and the Communist system behind it came crashing down.

"I knew there was something about Communism that was wrong," Robertson said. "It was contrary to the human spirit."

"It was a failed economic system, failed social system, failed moral system," he added. "Everything about it was wrong and I knew it would come down."

Not only did its collapse bring about an end to the Cold War, but a new opening. Christians were provided an opportunity to share the gospel with many eastern europeans who had never heard it.

Another memorable moment came four months later as Billy Graham and Pat Robertson met at the wall in Berlin.

"It was a historic moment and I was with a man who had declared that the gospel should be preached in eastern Europe," Robertson recalled. "He had gone over there and had been terribly criticized by people for doing that."

"He knew that those people were hungry for God and this was a place where the gospel would find root and it did," he continued.

Millions of east Europeans embraced Christianity and many are still flocking to churches. But is the window of opportunity over to spread the gospel?

"I don't think it's over, but it is not... near as wide as it was when the wall came down," Robertson said. "Those people were so hungry for spiritual reality. Now, they have become hungry for materialism."

The world has faced many challenges since that historic weekend in Berlin. Twenty years later, the Cold War has succumbed to prolonged hot wars in Iraq and Afghanistan and other difficult challenges are likely in the days ahead.

"We forget, we move on, but these moments of triumph in our history-- we need to emphasize," Robertson said. "it shows that a free people can triumph over totalitarianism if they're resolute and we had a resolute president and he won."