What bible verse speaks on life and death?

One instance of this thought can be found at: Revelation 3:1. It's a reminder for all Christians to be obedient to God and BUSY in his service(1 Corinthians 15:58).

Jesus is talking to the congregation in Sardis, explaining for THEIR (and OUR) benefit, that THINKING you're doing ok is not enough. You must be DOING what God says to do. (James 2:26)(Matthew 7:21-23)(Romans 10:10)(James 2:17) The members of the Sardis congregation may have THOUGHT they were 'alive', but because of their lack of 'works' they were dead in God's eyes.