Hi, Mulan,
I would recommend that a parent tell their children about Santa. It is the custom of this country and helps them lead a normal life. It adds to their childhood.
My two oldest regret being raised as JWs and not having a normal childhood.
My youngest was raised as a JW for a few years. He was originally told that Santa did not exist, and later was convinced that Santa did. So, he got one Christmas where he believed in Santa.
He figured out that the tooth fairy did not exist by simply leaving a tooth under his pillow and not telling his parents. Similarly, he figured out that Santa does not exist.
I told him this year that Santa does not exist, mainly because he already figured it out, and because at his age, he could be teased. I told him that the whole tooth fairy/Santa thing is really done by the Easter Bunny who has to have something to do the rest of the year. He laughed about that.
I think the best thing to do is abide by the harmless customs of our countries, so our children can have normal, healthy lives.
As for it being a lie, even JWs lie. Read the definition of a Lie in the Insight book. It leaves plenty of room for deception. Even this liberal defintion of a lie allows parents to tell their kids that Santa is real. Who says a three year old is "entitled to know the truth of the matter"?
What is a lie, a fib, a social custom? We generally consider a lie to be bad. But most people will lie when telling a fib, perhaps as part of a prank or to get someone to a surprise baby shower.
Some social customs demand we lie. When I was a loyal JW, a sister asked me, in front of an entire bookstudy group, if she looked like she lost five pounds. The truth is, I thought she had gained five pounds. To be "honest and righteous", I would have crushed her feelings. Instead, I lied. I told her that I agreed. She was pleased. I was just glad I did not hurt her feelings.
Elders have lied to me about why I didn't get certain priviledges. They were trying to spare my feelings.
Even the JW yearbook gives several examples of JWs lying, mostly to "Jehovah's enemies". There are some examples of brothers lying to a CO because it was a custom in that country not to say anything that would make someone feel bad. The example was held out as an interesting experience in the CO work, and nothing was said about the brothers having "lied" to the CO.
Richard