Philosoraptor

He already did, in the person of Christ.

We were the "aliens" (we had alienated ourselves from God through sin). Christ was the reconciler, and Mediator to bring back those who were alienated from God.

If you think logically, according to the two definitions provided by google,

1. A foreigner, especially one who is not a naturalized citizen of the country where he or she is living
technically yes, Jesus would be an alien of sorts

2. A hypothetical or fictional being from another world
then no (at least in my worldview) God or Jesus is not an alien