The Environment Envir. There was no magic in their changing their minds. There was the power of the Holy Spirit touching their hearts as they heard the message. Actual change takes place slowly for some and for others it is an immediate point of action that can be observed over time.
Reform is the word that describes the change in persons life.
Don't confuse reform with repentance. Repentance is, an about face of the soul and a change of our will or mind. God, without any reservation of Scripture, expects everyone to change their mind about He and His Son. If a change in mind takes place, it logically would be predicated by a knowledge of what one is to be changing from and changing to. When Peter told these people in Acts 2 to repent, they had already heard a messaged from Peter and perhaps the other Apostles.