Criticism

Christian opposition
Despite Santa Claus's mixed Christian roots, he has become a secular representation of Christmas. As such, some Protestants dislike the secular focus on Santa Claus and the materialist focus that gift giving brings to the holiday. Such a condemnation of Christmas is not a 20th century phenomenon, but originated among some Protestant groups of the 16th century and was prevalent among the Puritans of 17th century England and colonial America who banned the holiday as either pagan or Roman Catholic. Christmas was made legal with the Restoration but the Puritan opposition to the holiday persisted in New England for almost two centuries.

Following the Restoration of the monarchy and with Puritans out of power in England, the ban on Christmas was satirized in works such as Josiah King's The Examination and Tryal of Old Father Christmas; Together with his Clearing by the Jury (1686)
Rev. Paul Nedergaard, a clergyman in Copenhagen, Denmark, attracted controversy in 1958 when he declared Santa to be a "pagan goblin" after Santa's image was used on fund-raising materials for a Danish welfare organization. One prominent religious group that refuses to celebrate Santa Claus, or Christmas itself, for similar reasons is the Jehovah's Witnesses. A number of denominations of Christians have varying concerns about Santa Claus, which range from acceptance to denouncement.
Some Christians prefer the holiday focus on the actual birth of Jesus, believing that Christmas stemmed from pagan festivals such as the Roman Saturnalia and Germanic Yule that were subsumed within ancient Christianity. An even smaller subset of Reformed Christians actually prefer the secularized version of the holiday for the same reasons, believing that to relegate Christ's birth to Christmas is wrong.

Symbol of commercialism
In his book Nicholas: The Epic Journey from Saint to Santa Claus, writer Jeremy Seal describes how the commercialization of the Santa Claus figure began in the 19th century. "In the 1820s he began to acquire the recognizable trappings: reindeer, sleigh, bells," said Seal in an interview. "They are simply the actual bearings in the world from which he emerged. At that time, sleighs were how you got about Manhattan."
Writing in Mothering, writer Carol Jean-Swanson makes similar points, noting that the original figure of St. Nicholas gave only to those who were needy and that today Santa Claus seems to be more about conspicuous consumption:
"Our jolly old Saint Nicholas reflects our culture to a T, for he is fanciful, exuberant, bountiful, over-weight, and highly commercial. He also mirrors some of our highest ideals: childhood purity and innocence, selfless giving, unfaltering love, justice, and mercy. (What child has ever received a coal for Christmas?) The problem is that, in the process, he has become burdened with some of society's greatest challenges: materialism, corporate greed, and domination by the media. Here, Santa carries more in his baggage than toys alone!"

In the Czech Republic, a group of advertising professionals started a website against Santa Claus, a relatively recent phenomenon in that country. "Czech Christmases are intimate and magical. All that Santa stuff seems to me like cheap show business," said David König of the Creative Copywriters Club, pointing out that it is primarily an American and British tradition. "I'm not against Santa himself. I'm against Santa in my country only." In the Czech tradition, presents are delivered by Ježíšek, which translates as Baby Jesus.
In the United Kingdom, Santa, or Father Christmas; was historically depicted wearing a green cloak. More recently, that has been changed to the more commonly known red suit. One school in the seaside town of Brighton banned the use of a red suit erroneously believing it was only indicative of the Coca-Cola advertising campaign. School spokesman Sarah James said: "The red-suited Santa was created as a marketing tool by Coca-Cola, it is a symbol of commercialism." In reality, the red-suited Santa was created by Thomas Nast.

Controversy about deceiving children
"The adults they count on to provide reliable information about the world introduce them to Santa. Then his existence is affirmed by friends, books, TV and movies. It is also validated by hard evidence: the half-eaten cookies and empty milk glasses by the tree on Christmas morning. In other words, children do a great job of scientifically evaluating Santa. And adults do a great job of duping them."

Woolley posits that it is perhaps "kinship with the adult world" that causes children not to be angry that they were lied to for so long. The criticism about this deception is not that it is a simple lie, but a complicated series of very large lies. The objections to the lie are that it is unethical for parents to lie to children without good cause, and that it discourages healthy skepticism in children. With no greater good at the heart of the lie, it is charged that it is more about the parents than it is about the children. Writer Austin Cline posed the question: "Is it not possible that kids would find at least as much pleasure in knowing that parents are responsible for Christmas, not a supernatural stranger?"
Others, however, see no harm in the belief in Santa Claus. Psychologist Tamar Murachver said that because it is a cultural, not parental, lie, it does not undermine parental trust. The New Zealand Skeptics also see no harm in parents telling their children that Santa is real. Spokesperson Vicki Hyde said, "It would be a hard-hearted parent indeed who frowned upon the innocent joys of our children's cultural heritage. We save our bah humbugs for the things that exploit the vulnerable." It can also be advocated that, although Santa Claus isn't real, the Christmas spirit is real.
Dr. John Condry of Cornell University interviewed more than 500 children for a study of the issue and found that not a single child was angry at his or her parents for telling them Santa Claus was real. According to Dr. Condry, "The most common response to finding out the truth was that they felt older and more mature. They now knew something that the younger kids did not".
The other side of the debate concludes with another referenced quote of:
There are three stages of a man’s life: He believes in Santa Claus, he doesn’t believe in Santa Claus, he is Santa Claus. - Author Unknown
A further advantage of the Santa Claus deception is that it has provided a useful model for explaining that other beliefs in the supernatural might be equally false; one should not blindly accept any belief.