(Provided they follow the ten commandments like 'thou shalt not kill', being pure vegetarians etc)
Shrila Bhaktivedanta Svami Prabhupada's
Letter to Bhagavan das -- Los Angeles 2 March, 1970:
"Regarding the end of devotees of Lord Jesus Christ, they can go to heaven, that is all. That is a planet in the material world. A devotee of Lord Jesus Christ is one who is strictly following the ten commandments. Now just like in the commandment "Thou shalt not kill" this is a moral instruction for the sinful man. Similarly Lord Buddha also emphasized ahimsa paramadharma "the highest religion is nonviolence." So these instructions are for the sinful men. When one is pious, instead of being sinful, he is promoted to the higher planetary systems like Janaloka, Mahaloka, or Tapaloka and they are above the planet Svargaloka. So persons who are cleansed of sinful life become eligible for spiritual life. From the instructions of Lord Jesus Christ we find that the stress is given to make men free from sinful life—such as "Thou shalt not kill" "Thou shalt not covet"—like that.
Therefore the conclusion is that the devotees of Lord Jesus Christ are promoted to the heavenly planets which are within this material world."