'Unto' in the Bible

Fear nothing of what thou art about to suffer. Behold, the devil is about to cast of you into prison, that ye may be tried; and ye shall have tribulation ten days. Be thou faithful unto death, and I will give to thee the crown of life.

And he that overcomes, and he that keeps unto the end my works, to him will I give authority over the nations,

Behold, I stand at the door and am knocking; if any one hear my voice and open the door, I will come in unto him and sup with him, and he with me.

and they have overcome him by reason of the blood of the Lamb, and by reason of the word of their testimony, and have not loved their life even unto death.