Faithful in God's work and keep his words

Revelation 3:7-13
Letter to Philadelphia
Who is holy and true, who holds the key of David, What he opens no one can shut, and what he shuts no one can open.
Obey the words of God:
I have placed before you an open door that no one can shut. I know that you have little strength, yet you have kept my words and have not denied my name. I will keep you from the hour of trial that is going to come upon the whole word to test those who live on the earth.
Encouragement:
I am coming soon. Hold on to what you have, so that no one will take your crown.
Him who overcomes I will make a pillar in the temple of my God. Never again will he leave it.
Philadelphia is present-day Alacehir in Turkey. This letter, like the letter to Smyrna, contain no word of blame.

Why?
Destroyed by earth quake.
Key of David: Isaiah 22:21-22 , power and truth.
To judge by these letters, it is not the biggest, most impressive-looking churches, or those with most prestige威望, which are necessarily in best spiritual shape. Christ opens the door for effective work, not to those who are strong, but to those who are faithful.
How?
The blessing will come to church for effective work and Christ opens the door, so as to a Christian who are faithful in God's work and keep his words.

Philadelphia was the least distinguished of the cities of the Seven Churches. It was the latest to take on importance as a city, and only a few ruins are visible now. However, on the positive side, it was located on the outer edge of Hellenistic civilization and the Christian faith, and therefore had grave responsibilities for spreading the thought patterns and activities of these transforming powers. Furthermore, Philadelphia andSmyrna were the only two churches among the Seven about which nothing bad was said by John.