In the Mahabharata, the scripture around Lord Krishna, the second human incarnation of God the Holy Father, Isa is listed as one of the many names of Bramha, the Creator who emerged out of Vishnu's navel. Vishnu is God above all. Isa, of course is the name for Jesus in the Koran. Jesus was Greek for Yeshua, which is the name Mother Mary used to address her son. Vishnu is simply the Holy Father in the Christian belief system. Muslims call him Allah, or simply God. Since He is the only, He does not need a name.