Why are you being so rigid? God just wants you to be good. He does not care about all those extra rules. He will not frown if you skip Mass and come to church with us.
Protestant family and friends make these comments and it is often difficult to explain why we choose to stand firmly with the Church instead of bending the rules a bit. Reflecting on Pentecost offers some answers. Pentecost is the beginning of the Church. The Apostles were gathered with Mary in prayer. They were afraid. But they were faithful. Their faith was rewarded with the Paraclete. Christ had promised to send the Holy Spirit and through the grace of the Spirit the apostles were able to conquer their fears and fulfill the Great Commission--to go forth, proclaim the Gospel, and baptize in the name of the Father, the Son, and the Holy Spirit. They did not go forth as individuals, but rather as servants of the Mystical Body of Christ, the Church. And the head of this Church was Peter.
There is much scriptural evidence of the primacy of Peter. The most direct statement is Matthew 16:18-19:
And so I say to you, you are Peter, and upon this rock I will build my church, and the gates of the netherworld shall not prevail against it. I will give you the keys to the kingdom of heaven. Whatever you bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven.
Christ never meant for us to cultivate our faith alone as individuals. Rather, he gave us his Church. He gave us one, holy, catholic and apostolic Church. Pope Benedict addressed this in his Pentecost homily:
But let's look at today's Gospel in which Jesus affirms: “When he comes, the Spirit of truth, He will guide you to the whole truth”. Speaking about the Holy Spirit, Jesus is explaining to us what the Church is and how she must live in order to be herself, to be the place of unity and communion in Truth; he tells us that acting like Christians means not being closed inside our own spheres, but opening ourselves towards others; it means welcoming the whole Church within ourselves or, better still, allowing the Church to welcome us. So, when I speak, think and act like a Christian, I don't stay closed off within myself – but I do so in everything and starting from everything: thus the Holy Spirit, the Spirit of unity and truth, can continue to resonate in people's hearts and minds, encouraging them to meet and welcome one another. Precisely because it acts in this way, the Spirit introduces us to the whole truth, who is Jesus, and guides us to examine and understand it. We do not grow in understanding by closing ourselves off inside ourselves, but only by becoming capable of listening and sharing, in the “ourselves” of the Church, with an attitude of deep personal humility. Now it's clearer why Babel is Babel and Pentecost is Pentecost. Where people want to become God, they succeed only in pitting themselves against each other. Where they place themselves within the Lord's truth, on the other hand, they open themselves to the action of his Spirit which supports and unites them.
So whenever I act outside the norms of the Church, I am placing myself outside of the influence of the Holy Spirit. I am trying to go it alone and behave like the builders of the Tower of Babel. This is never advantageous. Therefore, in matters great and small I seek for myself and my family to act in one accord with the Church. How can I want to do otherwise?