Chapter ten begins with a complex illustration: contrasting a thief who illegitimately attempts to gain access to a flock of sheep with the animals' true Shepherd (10:1-6). The thief mentioned in verses one and eight is anyone who attempts to lead the sheep—meaning the people of God—into a false religion (several Church Fathers give as examples Judas of Galilee and Theudas (see Acts 5:36), who led failed Jewish rebellions against Rome in 6 AD (Judas) and 46 AD (Theudus)). Such a dangerous individual does not enter through the door—referring to both Holy Scripture and Christ Himself (see John 10:7)—and, being a stranger, frightens the sheep. In contrast to such an underhanded, misleading way of approaching God's people, the true Shepherd—Jesus Christ—is both known by His sheep and knows each of them by name.
Jesus then directly contrasted the works wrought by the thieves with those of the Good Shepherd: the thieves come only to steal and destroy, while the Good Shepherd comes not only to give life to His sheep, but even to die for them (10:10-11). The Good Shepherd's concern for the sheep also differs from that of the hireling (meaning people who become leaders in the Church because they want power or glory): hirelings abandon the sheep at the first sign of persecution from the wolf (referring to Satan) (10:12-13). Only Jesus Christ, the Good Shepherd Who knows and is known by God the Father (10:15), willingly sacrifices Himself for His sheep (and also is the only one Who, after laying down His life, has the power to take it up again (10:18)).
St. Cyril of Alexandria points out the deep significance for us of our relationship to Christ the Good Shepherd, and Christ's relationship to the Father:
(Christ's words in verses 14-15 are) equivalent to saying, 'I shall enter into a close relationship with My sheep, and My sheep shall be brought into a close relationship with Me, according to the manner in which the Father is intimate with Me, and again I also am intimate with the Father'...Through our relationship with the Son, we are related to God the Father, because the Only Begotten, Who is God of God, was made man, and though separate from all sin, He assumed our human nature.
After this the chapter jumps ahead two months. People asked Jesus to tell clearly them if He is the Christ, the promised Messiah Who would save His people (10:24). Jesus responded that He had already stated this, but they refused to believe Him; this disbelief comes from the fact that they were not among the sheep who follow the Good Shepherd (10:25-27). Those who belong to the Good Shepherd were given to Him by the Father, and therefore are assured of eternal life (10:28).
The people then became enraged when Jesus claimed to be God (10:30-33). This reaction is absurd, because not only did the people (in the words of Blessed Theophylact) "approve men who have been deified by grace and (called) gods" (see Christ's reference in 10:34 to Psalm 81:6), but Jesus also did the work of the Father (10:37-38). Furthermore, all the things prophesied by St. John the Forerunner about Christ were true (10:41).