Krishna is a universal Godman, and those who partake of "One Mind Soul"-realization are Godmen (or, in today-speak, "Godpeople").
Guru Nanak's famous statement, "You will need a Godman" applies to all religions and faiths, even Confucianism (God-realization as the Immortals (e.g., the Yellow Emperor) was a motivation of Confucius, who desire to "prove all things" or "work out his salvation with diligence").
As to the "halo" or nimbus (to use another term: http://en.wikipedia.org/wiki/Halo_(religious_iconography) ) is a visual reality (e.g., Pope Leo XIII in later 19th century was seen on occasion to have a visible golden halo), it may be investigated or described somewhat in terms of the physics of Light. There are certain mathematical sureties which determine a halo's shape, and certain energies which produce such Realization. Related: "The Physics of the Soul," "Light Is a Living Spirit," "The Path of the Higher Self."
Sri Ramakrishna, a Godman, was visited by Christ Jesus, and noted His nose was somewhat more aquiline than in the painting Sri Ramakrishna had seen (Sri Ramakrishna also experienced God-realization in the tradition of the Prophet Mohammad (owbp), and was speechless for three days following).
The Buddhist monks of Tibet have a tradition re "Saint Issa," aka Christ Jesus: http://encyclopedia.summitlighthouse.org/index.php/Issa
Paramahansa Yogananda, an Avatar of Divine Love, visited Saint Therese of Neumann during the Third Reich difficulties, and they understood each other very well. The visit is described here: http://www.ananda.org/autobiography/#chap39
In general, there is a Oneness or "Community of the Holy Spirit" experienced by those of every faith, with divine Love, God-Obedience, and other such being the "order of the Day." Somewhat less than this, are those Saints and religious who are practiced in the realizations and truths of their respective faith, and who are studying to understand other Teaching.