This noun denotes simplicity or sincerity, a straightforward, uncomplicated disposition free from duplicity. Luke describes the early believers in Acts 2:46 as eating together 'with gladness and simplicity of heart' (ἀφελότητι καρδίας). The term evokes a childlike directness and communal authenticity—no social pretense, no calculated networking, just genuine fellowship. Classical usage emphasizes unworldliness and lack of sophistication. Luke paints an idealized portrait of the Jerusalem church's common life, marked by joy and ἀφελότης—a pure, transparent togetherness rooted in shared devotion to Christ.