In the Gospel from the Mass (John 10:1-10), Jesus warns the Pharisee “sheep rustlers” and makes it clear that He (Jesus) is the only true way to salvation:

[1] “Truly, truly, I say to you, he who does not enter the sheepfold by the door but climbs in by another way, that man is a thief and a robber. [2] but he who enters by the door is the shepherd of the sheep.  [3] To him the gatekeeper opens; the sheep hear his voice, and he calls his own sheep by name and leads them out.  [4] When he has brought out all his own, he goes before them, and the sheep follow him, for they know his voice.  [5] A stranger they will not follow, but they will flee from him, for they do not know the voice of strangers.”

[6] This figure Jesus used with them, but they did not understand what he was saying to them. [7] So Jesus again said to them, “Truly, truly, I say to you, I am the door of the sheep.  [8] All who came before me are thieves and robbers; but the sheep did not heed them.  [9] I am the door; if any one enters by me, he will be saved, and will go in and out and find pasture.  [10] The thief comes only to steal and kill and destroy; I came that they may have life, and have it abundantly.”

Jesus makes a clear statement that salvation only comes through Him.  Consider:

As has always been the case as Jesus makes clear, there are “sheep rustlers” who wish to lead the sheep away from Christ.

For today’s sheep, the “sheep rustlers” take many disguises: secular atheists who promise socialist utopias, false Christianities that promise prosperity without the pain or a “non-judgmental Jesus” who supports all kinds of perverted behaviors, false religions who deny the divinity of Jesus Christ, religion factions that justify and commit acts of murderous terrorism and good ‘ole materialism.  The “sheep-rustlers” are legion.

All these “sheep rustlers” seek to draw the sheep away from Jesus Christ.  Jesus condemns them and promises that if a person really wishes to be saved, there is only One Shepherd, One Gate, One Way; Salvation only comes from Jesus who’s name literally means “God Saves.”