The contrast is instructive. Matthew was called to follow, and he did. And so did many avowed sinners who heard the call down through the ages. The Pharisees, known for their focus on ritual purity, were clearly puzzled, and this explains why they had hung about for the most part. Their relationship with God was too much defined by their rituals, ultimately expressed in the Temple sacrifice. Turning this on its head, Christ calls us to follow him, and he'll take care of the rest. He provides the sacrifice. He reveals himself, and the knowledge of God; we don't go about discovering him. He shares this knowledge intimately beyond head knowledge through the Holy Spirit and the sacraments, especially in the Eucharist, where we know him most intimately and in a "super-substantial" way as we receive him, body and blood, soul and divinity.
To simply be perfectly honest, I am still in need of the divine doctor who alone brings healing of my soul. "O happy fault" that this should mean that he attends to me most lovingly!