It is a phrase of biblical sound and doubtless of puritan origin, now used for the most part joculal

What is the phrase being described? (The one of biblical sound)

What is the book in which you saw this?

You must start to provide more information, particularly source and context.

It looks like an explanation or definition of the meaning of a phrase. When I say "definition" I mean like in a dictionary. In these, verbs are usually given as the base or infinitive form, not as a participle ("treated") as you suggested.

It is a phrase of biblical sound and doubtless of puritan origin, now used for the most part jocularly in the sense:

not treat with tenderness
punish
rebuke

WB my reaction was same as Con's: What text, where

I get the feeling this is a hit-and-run poster.

Thanks all.

No, I am not. I like this forums very much.

It's to be found here. From HW Fowler's Dictionary Of Modern English Usage

http://books.google.co.uk/books?id=hrtIDakUpA4C&pg=PT416&lpg=PT416&dq=It+is+a+phrase+of+biblical+sound+and+doubtless+of+puritan+origin,+now+used+for+the+most+part+jocularly+in+the+sense+not+treat+with+tenderness,+punish+or+rebuke.&source=bl&ots=ZS1j0QDbpE&sig=BgfZgfC7peXWzzRp2MeEwJEVaos&hl=en&sa=X&ei=7hyKUf3tLoOoO7OegIgP&ved=0CDMQ6AEwAQ

Apparently it relates to the phrase Deal Faithfully (with).

An example of the jocular use of that phrase is in a short story by MR James called "The Story of a Disappearance and an Appearance" which is in a collection of ghost stories called "A Thin Ghost and Others", published in 1919. That was a long time ago, as was the publication of Fowler, and I should advise the OP and anyone else who might wish to use the phrase "deal faithfully with" in its jocular sense, that this usage has completely vanished from modern English, and would be met with blank looks or misunderstood.

It is in a description of a Punch-and-Judy performance:

"The play began on the stroke of a quarter to three by the church clock. Certainly it was very good; and I was soon relieved to find that the disgust my dream had given me for Punch's onslaughts on his ill-starred visitors was only transient. I laughed at the demise of the Turncock, the Foreigner, the Beadle, and even the baby. The only drawback was the Toby dog's developing a tendency to howl in the wrong place. Something had occurred, I suppose, to upset him, and something considerable: for, I forget exactly at what point, he gave a most lamentable cry, leapt off the foot board, and shot away across the market-place and down a side street. There was a stage-wait, but only a brief one. I suppose the men decided that it was no good going after him, and that he was likely to turn up again at night.

We went on. Punch dealt faithfully with Judy, and in fact with all comers; and then came the moment when the gallows was erected [...]"

Thanks Con, now I understand what it's all about