Solomon Kane by Ramsey Campbell

Solomon Kane is a sixteenth century anti-hero created by renowned sword and sorcery author Robert E Howard (creator of Conan the Barbarian).
When Solomon Kane meets the Devil's Reaper, he postpones his fate by renouncing violence - a vow that is soon tested by the forces of evil. Compelled to once again strap on his weapons, he embarks on an epic journey of redemption.