You believe in your heart, which is your spirit man. Never does the Bible anywhere say you must feel something to be saved. You may or may not feel anything. The key is to believe. Renewing implies a change.
Feelings react to what one thinks.
One has to know he is insulted to get angry or one has to know there was a goof-up to feel foolish. One has to understand he is blessed to feel joy, and one has to understand he is a sinner or has sinned to feel remorseful or repentant with a desire to change. It is what you believe or think that counts. We must know we are sinners and are in need of being saved. You may have been told that you must do something, or give up some things, in order to get saved.