To be steadfast as a Christian means to be firmly fixed in your faith, not easily moved or shaken. It means to be loyal and faithful to God, even in the face of trials and temptations.

Paul writes in 1 Corinthians 15:58, "Therefore, my beloved brethren, be steadfast, immovable, always abounding in the work of the Lord, knowing that your labor is not in vain in the Lord."