What reason does John finally admit to for his behavior?

From the text:

"PROCTOR: (Pauses as he controls himself and looks at Elizabeth. Uncomfortable at the thought.) I like it not that Mister Parris should lay his hand upon my baby. I see no light of God in that man. I’ll not conceal it."

Proctor also criticizes Parris for his wasteful spending habits in church.

so what this is saying is that he admits to behaving in such a way because he was mad that parris touched his baby? who is his baby?

so what this is saying is that he admits to behaving in such a way because he was mad that parris touched his baby? who is his baby?

No, this is Proctor's way of saying that he dislikes Parris to the extent that he doesn't want the man to touch his baby, that this is the reason his son was not baptized. Hale was questioning Proctor as to why his youngest son had not been baptized, and the above quote was his answer.