Evan Roberts was greatly used during the revival in Wales in 1904. His approach was fairly simple to Christians: Confess your sin and get right with God.
Here is excerpt from the "The Welsh Revival" website (http://www.welshrevival.com/)
....Within a month he felt compelled to share this message of the reality of God and the possibility of complete forgiveness of sins with his home youth group at Moriah Loughor.
Summing up the message in 4 parts, Evan pressed it home to the astonished church
1. Confess all known sin
2. Deal with and get rid of anything ‘doubtful’ in your life
3. Be ready to obey the Holy Spirit instantly
4. Confess Christ publicly
By the end of the first week over 60 responded. By the end of the second week Evan had already started on a whirl-wind tour of the South Wales valleys with his team of 5 girl singers and within a year or so 100,000 converts were said to be added to the Welsh Church....