Jesus promised that He would send the Holy Spirit and that this Spirit would remain with us.

Jesus said to the Apostles the night of the Last Supper, “And I will pray the Father, and he will give you another Counselor, to be with you for ever, even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him; you know him, for he dwells with you, and will be in you” (John 14:16-17).