Bible Verses About Steadfastness: In striving for the faith of the gospel

Only let your conversation be worthy of the gospel of Christ: that, whether I come and see you, or, being absent, may hear of you, that you stand fast in one spirit, with one mind labouring together for the faith of the gospel.

Dearly beloved, taking all care to write unto you concerning your common salvation, I was under a necessity to write unto you: to beseech you to contend earnestly for the faith once delivered to the saints.