The following is an excerpt from The MacArthur New Testament Commentary on John 10.

So Jesus said to them again, “Truly, truly, I say to you, I am the door of the sheep. All who came before Me are thieves and robbers, but the sheep did not hear them. I am the door; if anyone enters through Me, he will be saved, and will go in and out and find pasture. The thief comes only to steal and kill and destroy; I came that they may have life, and have it abundantly.” (John 10:7–10)

Since the religious leaders had failed to understand His first figure of speech, Jesus said to them again, “Truly, truly, I say to you, I am the door of the sheep.” Sometimes the shepherd slept in the opening of the sheepfold to guard the sheep. No one could enter or leave except through him. In Jesus’ metaphor He is the door through which the sheep enter the safety of God’s fold and go out to the rich pasture of His blessing. It is through Him that lost sinners can approach the Father and appropriate the salvation He provides; Jesus alone is “the way, and the truth, and the life; no one comes to the Father but through [Him]” (14:6; cf. Acts 4:12; 1 Cor. 1:30; 3:11; 1 Tim. 2:5). Only Jesus is the true source of the knowledge of God and salvation, and the basis for spiritual security.

The Lord’s assertion, “All who came before Me are thieves and robbers,” does not, of course, include Israel’s true spiritual leaders (such as Moses, Joshua, David, Solomon, Ezra, Nehemiah, Isaiah, Jeremiah, Ezekiel, and Daniel, among many others). Jesus was referring to Israel’s false shepherds—her wicked kings, corrupt priests, false prophets, and pseudo-messiahs. However, the true sheep did not hear them; they did not heed them and were not led astray by them (see the discussion of vv. 4 and 5 above).

Then Jesus reiterated the vital truth of verse 7: “I am the door;” and He added the promise, “If anyone enters through Me, he will be saved” from sin and hell. Christ’s sheep will experience God’s love, forgiveness, and salvation; they will go in and out freely, always having access to God’s blessing and protection, and never fearing any harm or danger. They will find satisfying pasture as the Lord feeds them (cf. Ps. 23:1–3; Ezek. 34:15) on His Word (cf. Acts 20:32). In utter contrast to the thieving false shepherds who, like their father the devil (8:44) came only to steal and kill and destroy the sheep, Jesus came that they may have spiritual and eternal life (cf. John 5:21; 6:33, 51–53, 57; Rom. 6:4; Gal. 2:20; Eph. 2:1, 5; Col. 2:13), and have it abundantly. Perissos (abundantly) describes something that goes far beyond what is necessary. The matchless gift of eternal life exceeds all expectation (cf. John 4:10 with 7:38; see also Rom. 8:32; 2 Cor. 9:15).