[written on 07 June 2015, to answer Patheos Catholic’s request to answer #whyremaincatholic]
In the United States, recent research has shown that the Catholic Church is losing faithful to the category of “unaffiliated” – whatever that is. Here in Austria, we would say, the Catholic Church is losing faithful to the category “not-practicing,” or “bored,” or “uninterested”. Our Catholic faith is out of sync.
I beg to differ. I love my Catholic faith and I cannot live without it. I cannot live without the Eucharist, without the saints, without the balanced theology my faith provides, and without the church itself.
1. The Eucharist
In Edzard Schaper’s novel , the fourth king goes out with the other three kings to visit the newborn King of Israel, but he loses the others wandering around along the way, reaching out to the hurting and lost, giving away the treasures he had brought with him, but at then end… He finally remembers that this goal was to find the King of Israel, and he arrives just in time to meet our Lord carrying the Cross to Calvary. He follows him to Calvary, kneels down to give Him all he has, his heart. And I can do the same, each time I attend Holy Mass, and the moment of Consecration arrives: maybe I went astray, my thoughts took me far away, but now I can give to Him what is most important, my heart. Because He is really here, He is transforming this bread and this blood completely into His Body and His Blood, and He comes to me in Holy Communion – where else would I have this, except in the Catholic Church? Yes, also in the Orthodox Churches, but nowhere else!
And wherever I am attending Mass, I can follow the priest’s words and gestures, whether I understand the language or not, from Iceland to Spain, from Los Angeles to Hungary and even India. Catholic means universal, world-wide… And all over the world are churches where Our Lord remains in the Eucharist, so that we come and stay with Him. This is Christ’s humility; He waits for us to be His companions. This is my first school of prayer, understanding, Love.
2. We are standing on the shoulders of giants
… And giants in the Catholic faith are saints. I am thinking here first on all those who helped us to maintain and shape our faith through the centuries, like St. Jerome, St. Athansius, St. Augustinus or St. Thomas Aquinas. And then of all those came to bring us the Gospel like St. Cyrill and Methodius, St. Patrick, St. Boniface and St. Ansgar, and those that helped to literally rebuilt the Church in times of crisis like St. Francis of Assisi in the 10th century, or St. Petrus Canisius in the 16th century in the German-speaking area.
“Every saint has a past and every sinner has a future” said Oscar Wilde. Saints? Is this something we will ever attain? Not here on earth. Saints are in Heaven, we aren’t there yet. But the competition is on (see; 1 Cor 9, 24-27), God’s grace is assisting us. We need humility, strength, prayer, self-giving to others…. Our Church is good at letting us know and experience that we are sinners, but she also offers us in the sacrament of reconciliation (in confession) the means of God’s forgiveness and grace, and brings us back on the way to become a saint. Maybe. One day. In Heaven.
3. Faith and Reason
I am biologist and biochemist and belong to a family of scientists. Faith and science cannot contradict each other, because both of them relate to the same Truth, to God, they are like two books, the book of nature and the book of scriptures, that God uses to reveal Himself to us.
“Though faith is above reason, there can never be any real discrepancy between faith and reason. Since the same God who reveals mysteries and infuses faith has bestowed the light of reason on the human mind, God cannot deny himself, nor can truth ever contradict truth.” 
So far, so easy.
Three years ago, I entered into the science-faith dialogue with many Non-Catholics: this was one of the most enriching experiences of my life since it opened up a whole new world of different ways to read the book of Genesis (and St. Paul), to focus on the Authority of scriptures, I heard of Bible scholars and theologians never heard before and saw people following Christ in rather different ways. But is faith in contradiction to reason, as some say? And is there more than one Truth? Reality-check is needed. Therefore, this experience also deepened and enriched my own Catholic faith: faith can go beyond reason, but never against.
4. Empty churches and the Church
If we want to learn some truth about ourselves, we should read C.S. Lewis “The Screwtape Letters” . Screwtape is an experienced devil giving advice to his little nephew Wormwood how to make sure that his patient will be led “on the sure path to Our Father below”. Screwtape tells Wormwood that his patient who has started to attend church on Sunday that he should make sure that his patient only looks at the outside of things:
“Provided that any of those neighbours sing out of tune, or have boots that squeak, or double chins, or odd clothes, the patient will quite easily believe that their religion must therefore be somehow ridiculous. At his present stage, you see, he has an idea of “Christians” in his mind which he supposes to be spiritual but which, in fact, is largely pictorial…. Keep everything hazy in his mind now, and you will have all eternity wherein to amuse yourself by producing in him the peculiar kind of clarity which Hell affords.”
And of course we could add a lot more – let’s look at all the funny, out-fashioned people, nobody cool, young, stylish, well-educated is going to church anymore. Or you can find the church teachings too strict. Or too modernistic. Or only concerned with social activities, but not with spiritual growth – or just the other way round. Whatever. And then, all the scandals! The church should consist of saints – and then there are sinners. No, that is too much!
Screwtape really sees the Church quite differently:
“(T)he Church as we see her spread out through all time and space and rooted in eternity, terrible as an army with banners. That I confess is a spectacle which makes our boldest tempters uneasy. But fortunately it is quite invisible to these humans.”
This is how I try to see the Church each day: Founded by Jesus Christ, True God and True Man, built on the rock of Peter, spread out through all time and space and rooted in eternity, here on Earth and there in Heaven. And this is why I still stand by my Church.
 Edzard Schaper, The Legend of the Fourth King, Crossroads 1999
 Dei Verbum, 4. See Catechism of the Catholic Church, 159.
 C.S. Lewis, The Screwtape Letters