Better alternatives to evolution to explain the existence of species., page-406

The 2nd Man was from heaven exactly in the context that Luke explains;

And the angel came in unto her, and said, Hail, thou that art highly favoured, the LORD is with thee: blessed art thou among women.
And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS.
He shall be great, and shall be called the Son of the Highest: and the LORD God shall give unto him the throne of his father David:
Then said Mary unto the angel, How shall this be, seeing I know not a man?
And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy being which shall be born of thee shall be called the Son of God.

So, he is not yet the Son of God, 2nd Adam.
We have the plan of God -> to his word -> to the angel -> to Mary -> to the power of the Highest LORD GOD -> resulting in the birth of Jesus, 2nd Adam.
So the plan, word of God and power came down from heaven and produced the 2nd Adam.
That is the very context of -> the second man from heaven
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The Bible defines holy as something or someone that is separated (sanctified) and dedicated to serve and fulfill the will of God.