singleness of heart: a plain, unaffected openness with no pretense, calculation, or hidden motive
This word appears only once in the whole Bible. Luke uses it at Acts 2:46 to describe how the first believers shared meals together, doing so "with gladness and singleness of heart." Because it is so rare, its exact shade is debated, but the family of Greek words it belongs to points clearly in one direction.
At root the word draws on the picture of smooth, level, stone-free ground. Greek writers stretched that image to describe people and speech that are plain and unpretending:
- a simple style of writing
- an unadorned way of living
- an unaffected manner with nothing put on for show
So the core idea is a heart that is uncomplicated and transparent, without pretense or a hidden agenda.
A respected minority of scholars reads the word instead as "generosity," leaning on the surrounding verses, where the believers sell their goods and share everything, and on a related Greek word (ἁπλότης) that can mean open-handed giving. The best recent studies suggest this is not really a second meaning but the same thing seen from the outside: a heart that is plain and undivided will naturally share freely. Luke seems to describe both at once, an inner sincerity that showed itself in open, welcoming table fellowship.
Disputed
How to render and understand the word at Acts 2:46: as an inner disposition of plain, unaffected sincerity ("simplicity" or "singleness of heart") or as a visible practice of open-handed sharing ("generosity of heart"). The manuscript reading is uncontested; the disagreement is entirely lexical and contextual.
- majority"Simplicity" or "singleness of heart": the plain, unaffected inner disposition, following the consistent sense of the whole ἀφελ- word family and its lone non-Christian parallel in Vettius Valens.; BDAG (Danker, 3rd ed., 2000), s.v. ἀφελότης; LSJ, s.v. ἀφελότης; C. K. Barrett, The Acts of the Apostles (ICC); Joseph A. Fitzmyer, The Acts of the Apostles (Anchor Bible 31)
- minority"Generosity of heart": open-handed liberality, read from the immediate account of shared possessions in Acts 2:44-45 and the parallel with the Pauline word ἁπλότης, which can denote open-handed giving.; Henry J. Cadbury and Kirsopp Lake, The Beginnings of Christianity, vol. IV (1933); Richard I. Pervo, Acts (Hermeneia, 2009)
- minorityA single first-century virtue that modern English wrongly splits in two: a plain, undivided heart inseparable from the open sharing it produces, so "simplicity" and "generosity" name one disposition seen from two sides.; Craig S. Keener, Acts: An Exegetical Commentary, vol. 1 (Baker, 2012)