Christianisation was not a singular event but rather an extended process marked by its own ups and downs, achievements, and obstacles. Jerzy Kłoczowski elucidated that `the Christianisation of the Slavs, Scandinavians (Normans), and Hungarians was a lengthy process spanning hundreds of years` (…). Other scholars underscored the significance of monitoring shifts in mentality and the consolidation of Christian beliefs and ethics, which was `a lengthier process than the mere act of baptism`. (…) The objective of this publication is to present various studies conducted by Polish and Czech scholars. These studies illuminate specific aspects of the tortuous process of Christianisation, evangelisation, catechisation, debates, and controversies. They analyse these phenomena in the context of the Church`s dual confrontation: on one front with remnants of pagan cults, magic, and superstitions, and on the other front with heretical movements, particularly Hussitism. The focus of these papers is predominantly on the late Middle Ages. Due to the specificity of archaeological sources, we begin the presentation with an earlier phenomenon in the light of material evidence from Wiślica and other towns in Poland, namely with the funeral rite. This is an exemplary starting point on the difficult path of Christianization in the longue durée, especially since in later centuries the memory of the dead was still an area where two traditions clashed. (…) A comparative analysis of the process of Christianisation in Bohemia and Poland requires little justification, yet it has never been performed in such detail previously. Both neighbouring Slavic nations influenced each other, with Bohemia`s precedence in Christianisation not only providing a reference point for Poland, paved by the efforts of the Czech missionary St. Adalbert but also serving as a model for Christianisation during the initial phase of missionary evangelisation and the subsequent deepening of Christianization in the late Middle Ages. The latter process was shaped by the Prague milieu and the pre-Hussite Reformist movement in the Bohemian Church, along with the exchange of individuals, students, professors, and ideas. (…) We illuminate this multifaceted process primarily through sources less commonly utilised in medieval studies of both countries. Our focus centres on legal sources, sermons, pastoral writings, and, finally, archaeological sources (catechetical tables, preaching exempla, sermons, consistory sources, synodal resolutions, brotherhood statutes and resolutions (`Czech Brethren`), chronicles, legal opinions, parliamentary speeches, polemical treatises, biblical commentaries, as well as, more broadly, theological, archaeological, and funerary sources). Krzysztof Bracha Martin Nodl From the Introduction