Through this psalm we call out,
that I may enter through them
and give thanks to the Lord.
And comes the answer:
This is the gate of the Lord;
the righteous shall enter through it.
Jesus is both the door (John 10:9) and the one who has opened it. He died, and says, "behold I am alive forevermore, and I have the keys of Death and Hades." (Revelation 1:18) He has opened up heaven to all believers. The Te Deum expresses it beautifully:
When Thou tookest upon Thee to deliver man: Thou didst not abhor the Virgin's womb.
When Thou hadst overcome the sharpness of death, Thou didst open the Kingdom of Heaven to all believers.
"Open to me the gates of righteousness,