Doors, they are a physical reality and they hold many facts about life metaphorically. This proves true in Scripture.

In Matthew 6:6 we read the red words of Jesus instructing believers to use the door in order to acquire privacy for prayer. This is an important element of prayer because Jesus discourages the opposite type of prayer in the verse before (v.5) - "do not be like the hypocrites, for they love to pray standing in the synagogues and on the street corners to be seen by others." Get secluded with God.

Then in Mark 13:34, Jesus teaches for His own to be on guard and watch at the door for the return of the house owner.

Doors as barriers or obstacles are not to be feared with the Lord on your side. Jesus proved that to the resurrected body walls and closed doors were no problem as He appeared to the Disciples - 

"On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, 'Peace be with you!'" (John 20:19)

Since we do not have our resurrected bodies at this writing, the Lord may elect to send an angel to open the barricaded doors. Peter and the apostles were imprisoned for preaching The Gospel and according to Luke in Acts 5:17-23, God sent an angel to open those jail doors and told them to continue the good work.

Many citations of doors talk about the figurative aspect also. In particular, taking advantage of or walking through the door God has blessed you with is exemplified in such verses as 1 Corinthians 16:9; 2 Corinthians 2:12; Colossians 4:3 and Revelation 3:8.

There is also the lesson of shut doors or missed opportunities found in Matthew 25:10 and Luke 13:25. In the Matthew verse, half of the virgins miss the opportunity to leave with the groom when He returned. And in the Luke passage there will come a time when the owner of the house, Jesus, closes His door.

Jesus is The Door to "every good and perfect gift from above" (James 1:17). He is known as the "narrow door" from Luke 13:24 and calls Himself "the gate" or "the door" according to John 10:9 - "I am the gate; whoever enters through me will be saved. They will come in and go out, and find pasture." When Jesus describes Himself as The Way, The Truth and The Life in John 14:6 there is no doubt this lends support to the picture of the narrow door.

Jesus has made way for His people the Jews, but also all others who believe in His completed, sacrificial work and resurrection. These additional people are referred to as Gentiles in Scripture and Luke reports the successful outreach of Paul and Barnabas in Acts 14:27 calling the campaign "a door of faith" -

"On arriving there, they gathered the church together and reported all that God had done through them and how he had opened a door of faith to the Gentiles."

John, in writing the Book of Revelation, speaks about the open door of Heaven in chapter four, verse one. 

"After this I looked, and there before me was a door standing open in heaven. And the voice I had first heard speaking to me like a trumpet said, 'Come up here, and I will show you what must take place after this.'"

Because of the sacrifice and victory over life, death, Hell and the grave by Christ Jesus - this door is both a real door for believers to pass through and symbolic of Christ's provision of eternal redemption, restoration and cohabitation in Heaven.

If you would like the doors in your life to never be viewed as an overwhelming barrier then allow Christ Jesus to be the opener and closer of your doors. One of the most crucial keys that The Lord Jesus Christ purchased for humanity with His death, burial and resurrection was The Keys of Death and Hades. Jesus says in Revelation 1:18, "I am the Living One; I was dead, and now look, I am alive for ever and ever! And I hold the keys of death and Hades." No more fear of death or Hades.

However, of all the Keys the Lord Jesus possesses, the one that seems the most important - He does not forcefully use. Jesus paid for The Key to our Heart with His life, but He elects not to use it and awaits acceptance of His invitation as you hear His knock on the door of your heart and hear Him say, "Here I am! I stand at the door and knock. If anyone hears my voice and opens the door, I will come in and eat with that person, and they with me." - Revelation 3:20

God holds all the keys. He even has The Master Key for all the doors of your heart/life. He will unlock many a room inside your heart; He will open many a door in your life too - but first, you have to open up to Him, the front Door.