Complex sentence: Callahan, not having faith enough to do so, is soon overwhelmed by Barlow, who takes the now useless cross and snaps it in two, and Callahan is forced by Barlow to drink the vampire's blood.
Split into simpler sentences: Callahan, not having faith enough to do so, is soon overwhelmed by Barlow, who takes the now useless cross and snaps it in two. However, Callahan is forced by Barlow to drink the vampire's blood.