Many things wont be believed until there is a regeneration from the Holy Spirit when a person gets saved
you just dont have the Spirit living in you to teach you, to make it real
Repentance is not about belief, however, it is a heart attitude that acknowledges that God is, that God is Holy, that God is separate and distinct from us and that our sin separates us from Him
Repentance is the act of turning from sin, to God. God has a spiritual bar-code scanner, he can see who is repenting vs those who are just sorry they were caught.
Although you can be starting to believe, but that must be the starting of the laying of the foundation, known as repentence.