Are Western Laws and Christianity Discrete?

While reading the first sections of Becoming Sinners I continuously struggled with Robbins' account of how Christianity and acceptance of Western legal institutions arose in relation to one another; I specifically struggled with the way Robbins kept acceptance of Western laws and the rise of Christianity separate. For me it appeared that Robbins treated the acceptance of Western laws as lacking a strong, if any, influence on the acceptance of Christianity. Robbins seems to have neglected the fact that the Western legal tradition is predicated upon monotheistic religious values, often Christian values. The laws and institutions that the colonists presented to the Urapmin were originally based upon a set of religious values. When Robbins argues that the Urapmin incorporated these Western legal institutions, he should note that this was also a possible means by which Christianity could have been incorporated into Urapmin society. Perhaps the acceptance of these legal institutions, which predated the widespread Urapmin acceptance of Christianity, acted as a soft introduction to Christian values. When accounting for Urapmin conversion to Christianity, we should note their prior incorporation of Western laws and the morals that underlay these laws.