Tim Challies posted these comments from Sinclair Ferguson’s book The Christian Life: A Doctrinal Introduction (a book I have very much benefitted from reading). This is very helpful!

Sin. I can’t live with it, but am just not able to live without it. I know that I’ve been freed from sin, freed from the power of sin, and yet I still sin. Scripture tells me not to let sin reign, it tells me that if I am truly a child of God I will not go on sinning (Romans 6:12, 1 John 3:9). And still I sin. Even in those times that I focus my efforts on one particular sin I find that I am unable to stop, unable to put it entirely to death. My mind can’t do it; my will can’t do it. It may not reign as sovereign, but it continues to exist as a trial and a steady temptation.

In The Christian Life: A Doctrinal Introduction Sinclair Ferguson writes about this tricky relationship of sin to the Christian and offers these words of assurance: “We are no longer what we once were; we are no longer related to sin the way we once were.” This is important for me to understand and to keep in the forefront of my mind as I battle sin—any sin. I am not what I once was. I am not who I once was. I was once a slave to sin, owned by it, inexorably drawn to it. But now I am the slave to a different master. I am owned by God and subject to him. My relationship to sin has been radically transformed.

And yet I still get angry. I still lash out in anger. I still simmer in anger. I still have desires that stem from anger and suffer the consequences of my anger. And that is just one sin. I still lust and am still jealous and am still thankless and still sin in so many ways. I have died to sin but sin has not yet died within. But here is the difference; here is the change: Sin no longer has dominion. And practically I cannot relate to it as if it has dominion. I have to ensure that my experience of sin is consistent with my theology of sin.

Anger does not own me. Christ owns me. Lust does not motivate me. Christ motivates me. Jealousy does not get the final victory. Christ will get the final victory. The cross stands there as assurance that I have been saved from its power and will some day be fully and finally delivered from its presence. Sin is in me but I am in Christ. And what is in me was put upon him on the cross. He triumphed over it then. He broke its power. And now I just wait, battling all the while, for him to speak the word and bring it to an end once and for all.

Keven DeYoung quotes J. Gresham Machen on his blog. This is very applicable to our current study in Titus

Trampling Upon Human Hearts
Any Christian worth listening to loves the cross and is loath to see it robbed of its glory. To ridicule what the cross accomplished is to make war with the heart of the gospel and the comfort of God’s people.

J. Gresham Machen understood this well:

They [liberal preachers] speak with disgust of those who believe ‘that the blood of our Lord, shed in a substitutionary death, placates an alienated Deity and makes possible welcome for the returning sinner.’ Against the doctrine of the Cross they use every weapon of caricature and vilification. Thus they pour out their scorn upon a thing so holy and so precious that in the presence of it the Christian heart melts in gratitude too deep for words. It never seems to occur to modern liberals that in deriding the Christian doctrine of the cross, they are trampling upon human hearts. (Christianity and Liberalism, 120 [pagination may differ])

No doubt, some Christians get worked up over the smallest controversies, making a forest fire out of a Yankee Candle. But there is an opposite danger–and that is to be so calm, so middle-of-the-road, so above-the-fray that you no longer feel the danger of false doctrine. You always sound analytical, never alarmed. Always crying for much-neglected conversation, never crying over a much-maligned cross. There is something worse than hurting feelings, and that is trampling upon human hearts.