The Journalist hit him in the face. Presumably this was intended to stop him from running outside screaming and giving away their hiding place.
As Joe L. has pointed out in a comment, in the original source novel he was hit in the head with the handle-end of a meat cleaver.
"I have been still too long," he said, in a tone that must have
reached the pit, "and now I must bear my witness. Woe unto this
unfaithful city! Woe! Woe! Woe! Woe! Woe! To the inhabitants of the
earth by reason of the other voices of the trumpet----"
"Shut up!" I said, rising to my feet, and in a terror lest the
Martians should hear us. "For God's sake----"
"Nay," shouted the curate, at the top of his voice, standing likewise
and extending his arms. "Speak! The word of the Lord is upon me!"
In three strides he was at the door leading into the kitchen.
"I must bear my witness! I go! It has already been too long delayed."
I put out my hand and felt the meat chopper hanging to the wall. In a
flash I was after him. I was fierce with fear. Before he was halfway
across the kitchen I had overtaken him. With one last touch of
humanity I turned the blade back and struck him with the butt. He went
headlong forward and lay stretched on the ground. I stumbled over him
and stood panting. He lay still.