'Ineffective' in the Bible

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?

We know that our old self [our human nature without the Holy Spirit] was nailed to the cross with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin.