I struggled with that at first also. There is so much reference to “works of the law” that we have our mind fixed on the “law” when we read the word “works”. But look at this verse.
“Then said they unto him, What shall we do, that we might work the works of God? Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent.” John 6:28-29
That verse removes the requirement to think of the law when we read the word “works”. Works can be viewed as any action by man that is put forward as something we do that merits salvation. In that respect there is nothing we can do that would merit salvation other than “believe”. And even believing is still a function of the Spirit of God within us.
Absolutely no argument. That verse is VERY clear in John 6 and in many other places in the Gospels. Yet repentance "happens." That is why I called it a work done by God. It is part of being exposed to God's Holiness. His Work as He washes us clean in the Son's Blood. The shadow in the OT is Aaron and his sons putting their hands on the sin offering.