Is it permissible to offer from the sacrificial to non-Muslims or atheists?
Allah The Almighty ordains as follows about processing the sacrificial meat:
“We have appointed sacrificial camels and cattle among the symbols of Allah. There is much good in them for you. Pronounce the name of Allah upon them when they are lined up. When they fall down on their sides, eat from them and also feed those who do not ask and the poor. Thus, We have subjected these animals to you that you may give thanks.” (Al-Hajj/The Pilgrimage; 22:36)
That means; the owner, the rich, the poor, relatives, neighbors, etc. may eat from the meat of sacrificial. They do not have to be Muslims. Offering from the meat of sacrificial to non-Muslims may even be recommended to warm their hearts for Islam (see 9:60).