The Welsh Calvinistic Methodists of the 18th Century Evangelical Revival taught that Christians should know that they are saved. The leaders of this movement, Daniel Rowland, Howell Harris and William Williams drew on the rich, Bible-based Puritan theology of assurance. They taught that believers should dilligently seek the "witness of the Spirit" or full assurance of faith. Converts were gathered into Societies or Experience Meetings where they could share their experiences of the trials and joys of the Christian life. William Williams wrote a book on how these meeting were to be led and encouraged.
This question was to be put to those who wished to join an Experience Meeting:
Though you have not received the witness of the Spirit, yet are you seeking God with all your heart, and that with a constant disposition of the soul (not in fits of conviction), longing to lay hold on God, wanting nothing but Him alone, and counting all things loss that you may gain Him, not resting till you posess Him?
(The Experience Meeting by William Williams p. 35 Evangelical Press 1973.)
This hymn expresses an intense longing for full assurance of faith.
Speak, I pray Thee, gentle Jesus!
O, how passing sweet Thy words,
Breathing o’er my troubled spirit
Peace which never earth affords.
All the world’s distracting voices,
All the enticing tones of ill,
At Thy accents mild, melodious,
Are subdued, and all is still.
Tell my Thou art mine, O Saviour,
Grant me an assurance clear;
Banish all my dark misgivings,
Still my doubting, calm my fear.
O, my soul within me yearneth
Now to hear Thy voice divine;
So shall grief be gone for ever,
And despair no more be mine.
William Williams (1717-1791)