Can the cremains (cremated ashes) of a Christian be buried in a Jewish cemetery in a non-religious ceremony? The Christian was foundationaly important to the very existence and survival of Israel.
This is an interesting question.
It is not permitted to bury a non-Jew in a Jewish cemetary (see Gittin 61, Rashi and Ran; see Shulchan Aruch 362:5; Shut Tuv Taam Ve’daas 2:253; and see at length Darchei Choshen (Silman), Vol. 1, p. 425 ff).
However, some write that the principle of not burying a non-Jew among Jews applies to proper burial, and not to ashes alone (see Iggros Moshe, Orach Chaim Vol. 5, Yoreh Deah no. 56). This is based on Noda Biyhuda (89) who writes that there is no formal halachah of burying the ashes of the dead, and their internment is not considered an act of burial.
Yet, many discuss the issue of burying the wicked with the righteous even with regard to ashes (see Divrei Malkiel 5:140 (also concerning burial in a separate graveyard); Minchas Elazar 2:34; Achiezer 3:72; see also Chayei Olam, Kovetz, 5663). However, this discussion is specific to a Jew that requested that he should be cremated, and some of the basic reasons mentioned there would not apply to this question.
Therefore, there is room to be lenient if there is a need to perform the burial. The ashes should preferably not be buried next to Jewish graves, but rather elsewhere in the cemetery.