[FreeReign]

He was naturalized at birth 8 U.S.C. § 1401 The following shall be nationals and citizens of the United States at birth:

How is somebody who is naturalized at birth not a "natural born citizen"?

Definition: Naturalization – Acquisition of U.S. Citizenship Subsequent to Birth:

[Ray76]

Suggest you read Article II.

[Hostage]

See Post #73.

[MamaTexan]

How is somebody who is naturalized at birth not a "natural born citizen"?

Because a naturalized citizen is made a citizen by the laws of Man, which is by statute or edict.
This is a citizen AT birth.

A NATURAL born citizen is made such by the Laws of Nature. It is inherited by blood, so the citizenship of the child follows the citizenship of the NATURAL parents.
This is a citizen BY birth.

Ted Cruz is not a natural-born citizen.

[El Gato]

How is somebody who is naturalized at birth not a "natural born citizen"? Definition: Naturalization – Acquisition of U.S. Citizenship Subsequent to Birth:

Under the Constitution Congress only has power over naturalization. So if a person is a citizen at birth because of a statute passed by Congress, she/he must be considered naturalized at birth. BTW, here's another, legal, definition:

The process under federal law whereby a foreign-born person may be granted citizenship.

Here's another, from 1856.

NATURALIZED CITIZEN. One who, being born an alien, has lawfully become a citizen of the United States Under the constitution and laws.
2. He has all the rights of a natural born citizen, except that of being eligible as president or vice-president of the United States. In foreign countries he has a right to be treated as such, and will be so considered even in the country of his birth, at least for most purposes. 1 Bos. & P. 430.