“Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.” 2 Corinthians 5:17, KJV.
[In Matthew 5:3-10, the Beatitudes] remind us of certain primary, central truths about the whole Christian position … The Christian gospel places all its primary emphasis upon being, rather than doing. The gospel puts a greater weight upon our attitude than upon our actions … on what you and I essentially are rather than on what we do. Throughout the Sermon our Lord is concerned about dispositions. Later He is going to talk about actions; but before He does that He describes character and disposition…
A Christian is something before he does anything; and we have to be Christian before we can act as Christians … Being is more important than doing, attitude is more significant than action. Primarily it is our essential character that matters… it is an entire fallacy to … say, for example, ‘To be truly Christian I must take up and use Christian teaching and then apply it.’ That is not the way our Lord puts it. The position rather is that my Christianity controls me; I am to be dominated by the truth because I have been made a Christian by the operation of the Holy Spirit within…
You cannot read these Beatitudes without coming to that conclusion. The Christian faith is not something on the surface of a man’s life, it is not merely a kind of coating or veneer. No, it is something that has been happening in the very centre of his personality. That is why the New Testament talks about rebirth and being born again, about a new creation and about receiving a new nature. It is something that happens to a man in the very centre of his being; it controls all his thoughts, all his outlook, all his imagination, and, as a result, all his actions as well.
 John 3:3; Titus 3:5,6; 2 Peter 1:4
 The Christian’s essential nature has changed in his/her spirit; the practical outworking of this new disposition involves surrender and trust in the indwelling Christ (1 Thess. 5:23; Col. 1:27; 2 Peter 1:5-8). Character development occurs in the soul as the mind is renewed (Rom. 12:2), the will is surrendered (Luke 9:23), and the affections are placed on God (2 Cor. 3:17,18).
This article is from Martin Lloyd-Jones, Studies in the Sermon on the Mount, Vol 1, pp. 96-7. Quoted in Daily Readings from the Works of Martin Loyd-Jones, edited by Frank Cumbers, London: Hodder and Stoughton, 1970. “Dr. Martyn Lloyd-Jones (1899-1981)… is recognised by many to have been one of the finest British preachers of the twentieth century and was minister of Westminster Chapel, London, from 1938 until 1968.
His ministry was based on the clear and systematic teaching and preaching of the Bible, and it was this that has earned him the respect and affection of many throughout the world.” – http://www.mlj.org.uk [footnotes – J.B.W.]