Because we are prone to wander, we must make our calling and election sure.

John 13:18-30

18 I am not speaking of all of you; I know whom I have chosen. But the Scripture will be fulfilled, ‘He who ate my bread has lifted his heel against me.’ 19 I am telling you this now, before it takes place, that when it does take place you may believe that I am he. 20 Truly, truly, I say to you, whoever receives the one I send receives me, and whoever receives me receives the one who sent me.”

21 After saying these things, Jesus was troubled in his spirit, and testified, “Truly, truly, I say to you, one of you will betray me.” 22 The disciples looked at one another, uncertain of whom he spoke. 23 One of his disciples, whom Jesus loved, was reclining at table at Jesus' side, 24 so Simon Peter motioned to him to ask Jesus of whom he was speaking. 25 So that disciple, leaning back against Jesus, said to him, “Lord, who is it?” 26 Jesus answered, “It is he to whom I will give this morsel of bread when I have dipped it.” So when he had dipped the morsel, he gave it to Judas, the son of Simon Iscariot. 27 Then after he had taken the morsel, Satan entered into him. Jesus said to him, “What you are going to do, do quickly.” 28 Now no one at the table knew why he said this to him. 29 Some thought that, because Judas had the moneybag, Jesus was telling him, “Buy what we need for the feast,” or that he should give something to the poor. 30 So, after receiving the morsel of bread, he immediately went out. And it was night.