C.H. Spurgeon “The Perpetuity of the Gospel”, 1882
https://www.spurgeon.org/sermons/the-perpetuity-of-the-gospel
That is a good rule for all Christians which I saw in one of our Orphanage schoolrooms—"What would Jesus do?”
“What would Jesus do?” was a reference to Thomas à Kempis’ Imitatio Christi (The Imitation of Christ)
A.B. Simpson, founder of the Christian and Missionary Alliance Church, wrote both the lyrics and music of a Gospel Hymn "What Would Jesus Do" with a copyright date of 1891.
https://hymnary.org/text/what_to_do_we_often_wonder#pagescans
The phrase was repeated in 1896 by Rev. Charles M. Sheldon in a Sunday evening sermon at the Central Congregational Church in Topeka, Kansas.
“In His Steps: What Would Jesus Do?” was published the next year.
https://ia800802.us.archive.org/5/items/inhisstepswhatwo00shel/inhisstepswhatwo00shel.pdf
Lloyd-Jones believed the phrase was fundamentally flawed, reducing Jesus to a moral and ethical example rather than Savior of sinners through His atoning sacrifice.
He established in Studies of the Sermon on the Mount that it is impossible for an unregenerate person to “imitate” Christ.
In his sermon The One Mediator, on Ephesians 2:16 Lloyd-Jones made the point that Jesus Christ did not come into the world to show us how to live; He came to die on the cross to save helpless sinners from the wrath of God.
https://www.mljtrust.org/sermon/the-one-mediator/
A born again believer will become more and more Christ-like (an internal heart change manifested by love and actions) through the supernatural work of regeneration, union with Christ, and our obedience and cooperation with the Holy Spirit.
https://www.mljtrust.org/sermon/the-power-of-christ-within/
https://www.mljtrust.org/sermon/sanctification-gods-work-and-ours/
https://sites.google.com/site/anotherdaysjourneybackhome/gospel-holiness/grow-in-grace