I do not know what the scriptures say but i do not find any sense in all this. Hinduism is one of the most tolerant religions in the world and i find it hard to believe that it preaches something so absurd. A temple is the abode of God and who are we to prevent the entry of any human being into his abode??? We have crores devi devtas in hinduism which is a symbolic manifestation that we believe that every living being has God within it. I see no reason why non hindus should not be allowed into temples.