0571.  Strong's Dictionary Study

0571. apistos {ap'-is-tos}; from 1 (as a negative particle) and 4103; (actively) disbelieving, i.e. without Christian faith (specially, a heathen); (passively) untrustworthy (person), or incredible (thing): --that believeth not, faithless, incredible thing, infidel, unbeliever(-ing).[ql

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