1. (a.) Not believing; not giving credit.

2. (a.) Not believing on God or religion; specifically, not believing in the Christian religion.

3. (a.) Not observant of promises or covenants.

4. (a.) Not true to allegiance, duty, or vows; perfidious; treacherous; disloyal; not of true fidelity; inconstant, as a husband or a wife.

5. (a.) Serving to disappoint or deceive; delusive; unsatisfying.

Machiavellian agnostic ambidextrous apostate artful atheist atheistic capricious changeable changeful collaborative conscienceless crafty creedless crooked cunning deceitful derelict disaffected disbelieving dishonest disloyal double double-dealing double-faced double-minded double-tongued doublehearted doubting duplicitous FALSE false-principled falsehearted fickle fluctuating freethinking heathen heretical hypocritical inconstant incredulous infidel infidelic insincere irreligious minimifidian nonbelieving not true to nullifidian of bad faith pagan perfidious recreant renegade repudiative sceptical shifting shifty tergiversant tergiversating traitorous treacherous treasonable treasonous trothless two-faced unbelieving unchristian unconfident unconverted unconvinced unfaithful unloyal unreliable unscrupulous unstable unsteadfast untrue untrustworthy wavering without faith