The Christian's Only Comfort is the sermonic exposition of the Heidelberg Catechism by Theodore VanderGroe (1705-1784), a prominent divine of the Dutch Further Reformation. VanderGroe's exposition of the Heidelberg Catechism could be considered his magnum opus, and in some ways it was esteemed as highly by the godly in the Netherlands as The Christian's Reasonable Service of Wilhelmus à Brakel. In this able exposition of the Heidelberg Catechism, we find the unmistakable characteristics of the Dutch Further it is steeped in Scripture; it is very pastoral; and it promotes a robust, comprehensive form of Reformed piety.
Perhaps the best out of any work I've come across pertaining to experiential reformed exposition. Not only is the Catechism itself unique among other reformed documents in that regard, but VanderGroe brings out the doctrine and applies it in ways that pierce to the very heart and sanctify the work of the triune God in his believing people in ways that few others in his era have.
If you want a faith that's pretends it's based on Christ but really puts the entire responsibility upon yourself go pick up this book and sprint to hell with it