The paramount text for what 'believe' means is Genesis 15:6, where the Hebrew word is האמין. This word means to "support". Literally, "Abraham made his support with YHWH". So you see it means more than just to support facts, or make someone your support. It also means to support the someone. Similarly, the English word "commit" which is in the Lexicons and is used in the KJV for πιστευω means to commit one's support to a person as well as to be committed to that persons care. Now of course one will believe what God says if one is committed to him, but belief is not even half the story.
the Greek word has meta as its first syllable which means change. You can argue all you wish but that does not change (meta0 anything. When you are talking about what Jesus said in the NT you must use koine Greek. There is nowhere in the NT that says Repent of your sins it is not there. It is quite true I did not define what the word Repent is but Jesus did. So allow that change of heart and mind that leads to a change of direction so you can trust in rely on Jesus because he is the only way.