'Sure' in the Bible

And we believe and are sure that thou art that Christ, the Son of the living God.

Now are we sure that thou knowest all things, and needest not that any man should ask thee: by this we believe that thou camest forth from God.

because the words that you gave me I passed on to them. They have received them and know for sure that I came from you. They have believed that you sent me.

"Come this way and have breakfast," said Jesus. But not one of the disciples ventured to question Him as to who He was, for they felt sure that it was the Master.