Guidance is of two kinds
Guidance of Taufiq and it is totally from Allah, i.e. Allah opens one's heart to receive the truth (from disbelief to Belief in Islamic Monotheism).
Guidance of Irshad through preaching by Allah's Messengers and pious preachers who preach the truth i.e. Islamic Monotheism.
[From the explanatory section in the Interpretation of the Meanings of the Noble Quran in the English Language]
[QURAN MIRACLES] The Miracles of the Number 19 in Quran | Dr. Shabir Ally