Union with Christ - Hardcoverby Sung Rual Choi (Author) Understanding union with Christ as a frame of thought (as a motif or theme) is important for accessing Calvin's theology. While the union with Christ doctrine arises when Calvin explains the doctrine itself directly (especially in light of soteriology), the strong presence of this motif union with Christ (union with the Triune God) indicates its pervasiveness when other doctrines or theological themes are explained as well.