As nouns the difference between faithfulness and steadfastness
is that faithfulness is the state of being faithful; allegiance; loyalty; fidelity while steadfastness is loyalty in the face of trouble and difficulty.
faithfulness
English
Noun
(-)
The state of being faithful; allegiance; loyalty; fidelity.
steadfastness
English
Noun
Loyalty in the face of trouble and difficulty.
Steadfast resolution.