Also, he is a little hard to follow because of his economy of words. Each sentence is full of meaning, so he should not be skimmed over like we can do with the vast majority of books written now in the 21st Century.
Besides, this is not a book that both Christian and non-Christian will appreciate or understand at all. He is talking about the Biblical subject of killing sin, which even Christians have a hard time facing. Owen deals with all of the ways that we as human beings have of hiding, rationalizing, excusing, justifying our sin, and so forth. Owen knew his own heart and tendencies very well, and he is really sharing from his own experience as well as from the experiences of his congregation.
It would do us all well to take time to read this little book - just over 100 pages.
Here is one quote about the work of the Holy Spirit in the mortification of sin in believers. It is from pg. 100 of the PDF file found here.
"And this is the first thing that the Spirit does in order to
the mortification of any lust whatever, -- it convinces the soul of all
the evil of it, cuts off all its pleas, discovers all its deceits,
stops all its evasions, answers its pretences, makes the soul own its
abomination, and lie down under the sense of it. Unless this be done
all that follows is in vain. "