The study focuses on Pope John Paul II’s view of conversion as an essential aspect of holiness. It explores why he emphasises the personal conversion of a Christian to God, and in a broader context, how conversion relates to the recovery of humanity and human dignity. The reflection is based on the teaching of the Second Vatican Council, especially as presented in the documents Gaudium et Spes and Lumen Gentium. Conversion is viewed from the perspective of spiritual theology and the union between God and the human person and focuses on some related features from John Paul II’s ‘Trinitarian’ group of encyclicals. The reflection also examines the importance of Christian conversion to God as an internal process of transformation in the human person in the context of both internal ruptures and external existential threats.