Is the following atheist tactic good sportsmanship or not?

[McBell]

"NORTH BERGEN, N.J. (1010 WINS) – An atheist group that has paid for a large billboard outside the Lincoln Tunnel reading “You KNOW it’s a Myth” says it is targeting “closet” atheists as part of its Christmas season campaign.

The large billboard featuring a silhouette of a traditional manger scene is located on the New Jersey side of the tunnel and sponsored by a group called American Atheists.

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The billboard is causing some controversy among those in the Garden State.

“I don’t think it’s any good for the kids. I’ve got a 7-year-old daughter — she believes in Christmas,” one woman told 1010 WINS’ Terry Sheridan."
source


Video News report

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It seems to me that since theists set the bar with their billboards so much lower than where that billboard sits, I have to say that yes, it is in good sportsmanship.