Theotokos

Now to create this Magen David is good in terms of symbolic meaning, but what I need really is to have two figures (one obviously preferably female) to represent Gabriel and Mary.

Gabriel poses less of a threat.

My brother's middle name is Gabriel, so as a young Jewish boy he will be perfect in terms of race and "youthful beauty". Also as an angel, to have an old man would be weird, so Saul is a definite choice as a literal representation of the angel (whilst also making it personal and contemporary).

Mary is more of a problem.

If we take the bibles description of her she is described as a young woman.

Many people argue that she was in her young teens (maybe 13-15) and so I am debating whether to have her at this age, or even younger.

I feel that I might have a problem making her too young, but at the same time, it may be a good way to put this point across of her being so young.

Racially Jesus would have been most likely Galilean Jewish, so darkish skinned and more middle eastern looking. 

But he was the son of God.

Dude could've been green or some shit.

Who knows.

Mary on the other hand was human 100%.

I think.

I highly doubt she would have been white, and to give a further contrast between her and Gabriel, 

I am going to portray her as a young black girl.