Four short lines, and the whole poem is a joke at the expense of a boring sermon. A man stands in church and preaches to the "new pew," and by the end he has "taken much time." The title, "Time thief," gives the game away: the preacher is a crook, not because he steals money, but because he steals the congregation's minutes.
The wordplay is what makes it work. "Crook" and "took" rhyme, and the sounds of "pew" and "new" echo each other, so the lines themselves feel a little like a sermon droning on in neat, repeating patterns. "New pew" is a funny phrase too. It could mean the pew is freshly built, or it might hint at a newcomer sitting there, a captive listener.
The speaker sounds amused and a bit impatient, like someone glancing at their watch. The mood is dry and playful rather than angry. The poem is itself brief, which quietly makes its point: it says in a few lines what the preacher couldn't.