Many people are scooting along through life, riding on their "goodness" to get them to heaven.  Some aren't even counting on that!  Some reason that as long as their "good" outweighs their "bad", they must be OK with God.  Church attendance, Bible knowledge, or even service to others are going to do it, but God will only receive those who are actually reborn--new heart, new life, and only the power of God can allow us to make THAT segue!