'Fidelity' in the Bible

“Woe to you, [self-righteous] scribes and Pharisees, hypocrites! For you give a tenth (tithe) of your mint and dill and cumin [focusing on minor matters], and have neglected the weightier [more important moral and spiritual] provisions of the Law: justice and mercy and faithfulness; but these are the [primary] things you ought to have done without neglecting the others.

What then? If some did not believe or were unfaithful [to God], their lack of belief will not nullify and make invalid the faithfulness of God and His word, will it?

For I was greatly pleased when [some of the] brothers came [from time to time] and testified to your [faithfulness to the] truth [of the gospel message], that is, how you are walking in truth.

If anyone is destined for captivity, he will go into captivity; if anyone kills with a sword, he must be killed with a sword. Here is [the call for] the patient endurance and the faithfulness of the saints [which is seen in the response of God’s people to difficult times].