These pages, taken from Professor Lazzati's lectures to a group of young people at the Eremo San Salvatore above Erba (1977-86), propose a reflection that reaches the heart of the Christian experience. It consists of a vision and a resulting practice of life lived "in Christ, under the guidance of the Holy Spirit." The author, firmly anchored in Scripture, examines perennial themes of a believer's journey in the Triune God, revealed by the Lord Jesus. Faith and reason, with the crucial questions of truth and related freedom, constitute the "gateways" to the essential requirements of a believer's practice. This has crucial junctures in the virtues (theological, cardinal), in the way of relating to one's own corporeality, and, in short, in the law of love. The path outlined offers direct applications for the lay faithful, called to be the builder of a "city on a human scale."