Going to play devils advocate here about the billboard in the op. Its pretty non descript (meaning in context to the other one i posted which mocked Christianity clearly).
I can see how in secular atheistic thinking, that it could be seen as reaching out in this way-
Consider this, loads of people are alone at Christmas and can be depressed especially at that time of year and some even commit suicide at Christmas time, and i would think a great many atheist are estranged from family and or friends at Christmas time because of their lack of belief.
So, i could understand that (the one in the op) billboard as simply being a way to reach out to those without faith who are alone and feeling alone and it being nothing more than that.
Personally i would just drive right by a billboard like in the op and think nothing more of it than any advertisement, since its not going out of its way to offend, or mock Christians and Christianity.
The other one that i posted though, i would be angry if i saw it in person - because its intend is clearly to inflame and in bad taste and its sole purpose imo is to target children and trash Christmas and Christianity.
Huge difference.