In John Piper’s address on Robert Murray McCheyne he talked about the gospel key to pursuing holiness:

God had given McCheyne the gospel key to pursuing personal holiness.

He received it through the teaching of Thomas Chalmers. Chalmers was very concerned about excessive introspection in the pursuit of holiness. He knew that a believer cannot make progress in holiness without basing it on the assurance of salvation. And yet the effort to look into our sinful hearts for some evidences of grace usually backfires.

Chalmers said that glimpses into the dark room of the heart alone give no good prospect. Instead, he said we should

take help from the windows.

Open the shutters and admit the sun.

So if you wish to look well inwardly, look well out. . . . This is the very way to quicken it.

Throw widely open the portals of faith and in this, every light will be admitted into the chambers of experience.

The true way to facilitate self-examination is to look believingly outwardly.

McCheyne had written that down in a class and underlined the last sentence. So it is not surprising to hear him give his own counsel in similar terms:

Learn much of the Lord Jesus.

For every look at yourself take ten looks at Christ.

He is altogether lovely . . . .

Live much in the smiles of God.

Bask in his beams.

Feel his all-seeing eye settled on you in love.

And repose in his almighty arms.

This was the basic strategy in the pursuit of holiness. And he knew that the battle would have to be waged all the way to the end. He said to his people, “When a soul comes to . . . Christ, it is not made perfectly holy all at once. ‘The path of the just is as the shining light, that shineth more and more unto the perfect day [Proverbs 4:18].'”

He was often distressed by his own lack of holiness. But he knew that the battle would be won only in the gospel way of looking ten times to Jesus and “being transformed into the same image from one degree of glory to another” (2 Corinthians 3:18).