On Holy Thursday, I remember the gospel reading of John 13:27, it says after Judas received the piece of bread, Satan entered him: how can that be possible when Jesus has given him the bread ( body of Christ) ?! I felt really puzzled about it, I thought with Jesus in you, the devil should have no chance!
Fr. Francis' answer:
In this passage, Jesus gave Judas the Eucharist, the body, blood, soul and divinity of Himself. And it is said that with that Satan entered Judas. Obviously, Satan was not in the Eucharist.
When we receive the Eucharist, we are saying “yes” to be one with Christ, it presupposes a covenantal relationship with Jesus. It is an act of saying “yes” to die to myself, take up my cross, and follow Jesus unreservedly and whole-heartedly. I will nail my sin to the cross. I will rather die than to offend You Lord again.
It is for this reason that the Church always teaches that only one who is in the state of grace may receive Holy Communion; my life must correspond to my “yes” in receiving Holy Communion, that indeed my action corresponds to a life of commitment to Christ.
But if I have committed mortal sins, if my thoughts and desires are not to be one with Christ, St. Paul in 1 Cor 11 said that then by receiving Communion I will be receiving my own judgement. This is because I cannot be saying “yes” to be with Jesus in my action of taking Communion, but in actuality all along I have been saying “no” in my heart because of my refusal to be reconciled with Him. That is making a mockery of the Eucharist, making the Communion—Jesus Himself—a liar.
That’s what happened to Judas. He did not want to be in communion with Jesus. He took the Communion, and so ate his own judgement. So instead of benefiting from the salutary graces coming from the Eucharist, he hardened his heart and ran off to begin executing his plan of betrayal.