To John Proctor, those golden candlesticks represent two the things that he can't stand and tolerate more than just about anything else -- greed and hypocrisy.
John Proctor is a humble farmer. He works hard, loves his wife, is honest with his peers, and is a man that can be counted on. He's not perfect, because the reader learns that John committed adultery with Abigail Williams, but much like Hawthorne's Hester Prynn, John's sin has made him a better man.
Because of John's humble and hard working job, he doesn't see the need for fancy adornments. He also sees humility as important in others, especially a minister. So when Reverend Parris preached for weeks on end about needing golden candlesticks, it bugged John. John was also insulted by Parris actually spending hard earned church donations on golden candlesticks when the church already had candlesticks made by a devout member of the congregation. John Proctor thinks that Parris is a greedy man who preaches one thing (humility, etc.) and then does the opposite.
In fact, John's view of Parris is so damaged by the the candlesticks (and presumably other stuff too) that John won't have Parris baptize his third child.