'Sure' in the Bible

I am sure of this, that He who started a good work in you will carry it on to completion until the day of Christ Jesus.

To be sure, some preach Christ out of envy and strife, but others out of good will.

And since I am sure of this, I know that I will remain and continue with all of you for the sake of your progress and joy in the faith,

Only [be sure to] lead your lives in a manner [that will be] worthy of the gospel of Christ, so that whether I do come and see you or remain absent, I will hear about you that you are standing firm in one spirit [and one purpose], with one mind striving side by side [as if in combat] for the faith of the gospel.

And in no way be alarmed or intimidated [in anything] by your opponents, for such [constancy and fearlessness on your part] is a [clear] sign [a proof and a seal] for them of [their impending] destruction, but [a clear sign] for you of deliverance and salvation, and that too, from God.

Therefore, my dearly-loved friends, as I have always found you obedient, labour earnestly with fear and trembling--not merely as though I were present with you, but much more now since I am absent from you--labour earnestly, I say, to make sure of your own salvation.

So joyfully welcome him in the Lord and make sure you honor such people highly,

As to the rest, my brethren, rejoice in the Lord; the same things to write to you to me indeed is not tiresome, and for you is sure;