The readings for the fourth Sunday of Easter are taken from Acts 2:42-47; 1 Peter 2:19-25; and John 10:1-10.
Acts records the essence of the authentic Christian church: they continued steadfastly in the Apostles’ teaching, which produced connectedness, which was celebrated in the Lord’s Supper, where THE prayers were said (likely the Psalms plus intercessions and thanksgiving, as the NT instructs). Here is the door, which is Jesus. Jesus refers to this in the Gospel lesson.
Peter tells us still more about the door to the sheep, which Jesus IS. Yet another summary of the Gospel from Peter and worth reading again, word for word: “He committed no sin, neither was deceit found in his mouth. When he was reviled, he did not revile in return; when he suffered, he did not threaten, but continued entrusting himself to him who judges justly. He himself bore our sins in his body on the tree, that we might die to sin and live to righteousness. By his wounds you have been healed.”
John records Jesus describing Himself as THE door. Jesus protects His sheep from wolves, but also from hirelings who care nothing for the sheep. From the time of the Apostles, the church has trained, examined, and called pastors in order to assure that they have access to the sheep according to the Word and will of God. Though we do this imperfectly, the church endures because of its nature, its essential and enduring communion as described in Acts.