The Church of Sardis: What's in a Name?

What does the Lord want us to learn from His message to this church?
We come to the 5th church of seven in Asia Minor – the Church of Sardis. Here we see a church in such declension that the Lord Jesus describes it as "dead". At one time, it was a bright and burning witness, but now the life had nearly drained away entirely. But, blinded by hypocrisy, the church worked to keep up outward appearances, rather than turning to the Lord.
Still, there is hope if the professing Christians in Sardis will wake up and repent. All the while, there is a small minority of true-hearted disciples in this church, and the Lord has great words of comfort and hope for them.