In his book Newton on the Christian Life: To Live is Christ, Tony Reinke mentions Tim Keller, pastor of Redeemer Presbyterian Church, quite a few times throughout his book on John Newton. The reason for this is because “Timothy Keller claims John Newton as ‘the best pastor I’ve ever seen in my life,’ and cites Newton in more sermons than he does any other figure in church history except C. S. Lewis, Jonathan Edwards, and Martin Luther. In 2013, Keller credited Newton’s letters for this influence on his own ministry….”
In his letters he [Newton] is often blunt, yet always tender. He is remarkably humble and open about his own flaws, but never in a cloying or self-absorbed manner. He is therefore able to point others to the grace of Christ on which he himself clearly depends…. Newton’s letters have influenced both my pastoral work and my preaching. Newton did not simply call people to holy living, but he also did close analysis of their motives and showed them the specific reasons they were failing to obey God. Decades of constantly reading and re-reading the letters have taught me how to do better analysis of underlying motives, so that when the high doctrines of grace are preached and applied, they do not merely press on the will but change the heart.
Tim Keller on Spiritual Maturity
This is footnote 17 from Chapter 7, The Growth Chart of the Christian Life in Newton on the Christian Life:
A father or mother in the faith is someone who has learned through spending the time, through relentless passion, a deep yearning that is consistent. You finally start to penetrate. You have regular communion with him. You know the One who is from the beginning.
Put it this way: You’re babies until you understand the difference between grace and works.
You’re adolescents until you understand everything is necessary that he sends and nothing can be necessary that he withholds. You stop blubbering about the hardness of life. You learn how to live according to the bare Word of God.
Lastly, you become a father or mother in the faith when you start to learn the disciplines of prayer and communing with him, so you regularly are seeing his glory. . . . Spiritually, people very often want spectacular things. They want great preaching. They want a great church. They want miracles. They want to see dramatic things happening in their lives.
They don’t like the routines. They don’t like praying and reading their Bible every day. They don’t just like learning the truth. Don’t you see the spiritual babyness in you? You’re unstable. You’re undiscriminating. You’re easily fooled. You tend to be exhibitionistic. You tend to like the spectacular, and you don’t like the grind. These are marks of the average Christian. These are the characteristics of the average church congregation. All I’m urging you to do is to humble yourself and encouraging you to say, ‘Yes, this is true of me, but I’m going to outgrow it’ (sermon, ‘Principles of Christian Growth: Part 1’).