Defending Christianity in our time became unpopular, “private”, shy and... poor. Catholic fundamental theology – officially responsible for defending faith on behalf of the Catholic Church – is aware of being in crisis: crisis of identity and content, and... popularity. It needs a new overall structure: a new point of departure and a new “spirit”. It was offered by Joseph Ratzinger, Krzysztof Kaucha declares. Almost everything that has been recently used to undermine the Christian faith and Christianity is used by Ratzinger to… defend Christianity. Kaucha offers over a dozen arguments for Christianity based on Ratzinger’s writings (and his original thinking): the Christian axiom as an argument for Christianity, Jesus Christ as the proof of the existence of God, Divine Revelation as an unending proof of God’s existence, the alternative argument, the argument from definitive novelty, the argument from the absence of someone greater than Jesus, argument from truth, the anthropological argument, the argument from forgiveness, the argument “from reason”, the argument from faith, Ratzinger’s wager (in analogy to the famous Pascal’s wager), the argument from the whole truth (many times very painful for Christians) about Christianity, the argument from the whole truth (many times very shameful for Catholics) about the Church, comparative argument no. 1 (Christianity versus other Religions), comparative argument no. 2 (Christianity versus the ever more secularized world).