When the Lord, in His letter to the Philadelphian church, applies these same words to Himself, He is saying that His will cannot be opposed. He governs all events in the history of this planet. He will open some doors and close others. The doors He opens will remain open. The doors He closes are inalterably locked. No power on earth can contravene what He has determined.
The Lord then tells the Philadelphian church how He will use His power to open and close doors.
3:8 "I know your deeds. See, 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 word and have not denied my name."
The image of open and closed doors has been powerfully employed elsewhere in the New Testament. The apostle Paul used this imagery to describe his missionary efforts. On his second missionary journey, he attempted to go into the province of Asia to preach the gospel, but was disallowed by the Holy Spirit — a shut door. Then he tried to go into Bithynia, on the southern shore of the Black Sea, but again was not allowed by the Lord — another shut door.
But when Paul came to Troas he received a vision of a man from Macedonia beckoning to him, and from this vision he learned that the Lord had opened the door for him to enter Europe. Paul's commitment to enter that open door changed the course of the entire Western world, affecting all of civilization since that time. Because of that open door into Europe, Paul took the Christian faith north and west through Europe and into Italy. Thus the Christian gospel gained a major beachhead in Europe from which it eventually launched itself around the world.
Later, in 1 Corinthians 16:8, Paul writes, "But I will stay on at Ephesus until Pentecost, because a great door for effective work has opened to me, and there are many who oppose me." Ephesus was the capital of Asia, a region that was once a door tightly shut against Paul. But later, as he penned these words to the Corinthians, that door was wide open, and Paul chose to stay there to make the most of his opportunity.
1 Corinthians 16:8-9
8 I will remain in Ephesus [however] until Pentecost,
9 For a wide door of opportunity for effectual [service] has opened to me [there, a great and promising one], and [there are] many adversaries. AMP
In recent years, we have seen doors that were locked and barred for decades being suddenly flung open to receive the gospel. Against all human calculation and completely without warning, doors have opened in Poland, Germany, Romania, Czechoslovakia, Yugoslavia, Hungary, and the Soviet Union. In these countries, millions of people — starved for hope, truth, and meaning in their lives — are responding to the Christian gospel. In these countries, the door is open, and fresh, fragrant air is sweeping in.
At this point I have to make a correction to the New International Version's text: "I know that you have little strength." This is not what the Greek text says. The NIV takes one continuous thought and breaks it in two, which I think is unfortunate. I believe a more faithful rendering of this entire thought would be:
"I have placed before you an open door that no one can shut because you have a little power and have kept my word and not denied my name."
There is a cause-and-effect principle at work here. The Lord opened a door for the Philadelphian church because this church had fulfilled certain conditions: because they had "a little power," because they had kept the word of the Lord, and because they had not denied His name. When a church fulfills these conditions, a door for ministry is always opened.
The Philadelphian church had "a little power" — that is, it had discovered to some degree the power of the Spirit. The Lord is talking here not about human strength, but about spiritual power. This is the kind of power that comes from faith, from expecting God to act. The Philadelphian church was comprised of people who sensed that God could act in human events, and they looked for an opportunity, a way to respond, a door for ministry and service and evangelism to the world around them. They sought to bring others through that open door and into a rich and fulfilling relationship with Jesus Christ.
To me, Ephesians 2:10 is in some ways the most exciting verse in the New Testament. The apostle Paul says, "For we are God's workmanship [also translated "masterpiece"], created in Christ Jesus to do good works, which God prepared in advance for us to do." That is why you have been made and saved by Jesus Christ: to do good works, works of help, mercy, kindness, witness, love, comfort, counsel, and strength.
10 For we are God's [own] handiwork (His workmanship), recreated in Christ Jesus, [born anew] that we may do those good works which God predestined (planned beforehand) for us [taking paths which He prepared ahead of time], that we should walk in them [living the good life which He prearranged and made ready for us to live]. AMP