Albert Einstein died a long time ago but people still believe his views. Besides, I don't think Sagan is saying anything too complicated. Just that we don't know exactly how the universe came to be and that maybe there is no origin, if people can think god always existed why can't we think the universe always existed.
Ricktheheretic,
We really don't have to accept anyone's word about the origin of the universe, especially when the Bible tells us!!!
The Bible tells us that God, whose name, in English, is Jehovah, created the heavens and the earth, and all the things in it, Genesis 1:1, Acts 17:24, Revelation 4:11.
There is another point to understand here, Jesus was God's very first Creation, Colossians 1:15, Revelation 3:14. After God Created His Onlybegotten Son, He Created the other things in existence, through Jesus, and for Jesus, Colossians 1:15-18, 1Corinthians 8:4-6, Hebrews 1:1,2. Also consider Proverbs 8:22-31, which Scriptures are accepted by most Theologians, as speaking about Jesus, wisdom personified, the Master worker of creation.
Since Jesus was the first creation of God, the universe was created sometime after Jesus was created, so the Heavens had a beginning, just as Jesus did, John 6:57.
The true facts are; most of the theory's about the origin are silly, and most go against the basic scientific Laws that govern the Cosmos, knowledge that man has learned by study of the Creation.