Am I sinful if I throw away a turkey brought from a non-Muslim store, or is it better to give it as a gift to Muslims who believe in the permissibility of eating meat from non-Muslim lands?

If the turkey is slaughtered according to Islamic law by a Muslim or a person of the Book, then it is permissible to eat. It should not be discarded, but rather eaten or given as charity.

However, if it was stunned before slaughter, or slaughtered by someone other than a Muslim or a person of the Book, or if there is doubt about its slaughter, then it is not permissible to eat, as it is considered carrion. In such cases, it should be disposed of by throwing it away or feeding it to animals. It should not be given to a Muslim who is not cautious about such matters.