According to my understanding, God will be in His own form, but visible to the people in a form they think.
To a Christian, God will be in the form of Jesus
To a Muslim, God will be in the form of Nabi Nayagam
To a Parsi, God will be in the form of Agni.
To a Hindu in Maharashtra, He will be in the form of Ganesh
In Tamilnadu, He will be in the form of Karthikeya
In Bengal, She will be in the form of Durga
In AP, He will be in the form of Vishnu
In Kerala, He will be in the form of Ayyappa,
In Punjab, He will be in the form of Guru Nanak.
God will speak in His own language (we don't know) but will be received by all and decyphered into their respective mother-tongue.
God's message would be:
" Oh My beloved people, When I am one, why do you think me and worship me in different forms and fight between you on the name of religions. I live in the heart of all the creatures I created. I belong to no religion. You need not visit temple, church and mosque to offer your prayers. Just sit for a minute and chant the name of your parents who brought you to this world. More than me, your parents are your own first God. Respect them and care them till last. After your death, you will reach me to embrace you."
No life without Sun