'Steadfast' in the Bible
And He will establish you to the end [keep you steadfast, give you strength, and guarantee your vindication; He will be your warrant against all accusation or indictment so that you will be] guiltless and irreproachable in the day of our Lord Jesus Christ (the Messiah).
Nevertheless, he that stands steadfast in his heart, having no necessity, but has liberty regarding his own, and has so determined in his heart that he will keep his daughter, does well.
Therefore let anyone who thinks he stands [who feels sure that he has a steadfast mind and is standing firm], take heed lest he fall [into sin].
Therefore, my dear brothers, be steadfast, immovable, always excelling in the Lord's work, knowing that your labor in the Lord is not in vain.