The concept of Ātman is fundamentally opposed to what the Bible teaches about the soul, sin, salvation, and the nature of God.

You're putting Hindu ideas into Christ's teaching. At least give Him the courtesy of interpreting His words through His own culture and religion.

Moreover, this heresy completely misses the point of "Emmanuel", God *with* us, not God *is* us. What do you think I AM means?

Note that no Christian can agree with this, though any Hindu or other syncretic religion that cherry-picks and misinterprets as it pleases, can.