And Jesus's answer to them was that there was nothing they could do - that it is only God who can do so - Only God gives belief.
A spiritually dead person, which everyone is before becoming saved, of themselves, cannot believe - first they must be given
spiritual life by God.
He said this is the work: believe on the son of God. God doesn't give belief; he enables a person to believe. I believed in God when I was anti-Christian. The voice I was following then is the voice that opened my heart to believe that Christ is the truth. The holy spirit leads and tutors people before they become saved. No one can learn of the father except through the spirit, and if people come to Christ after learning of the father, then that can only mean that they are taught of the spirit of God before being saved.
It is written in the prophets, And they will be all instructed of God. Every [one] then hearing from the father, and having learned, comes to me. John 6:45