An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth generation shall they not enter into the congregation of the LORD forever: Deuteronomy 23:3

The nakedness of thy sister, the daughter of thy father, or daughter of thy mother, whether she be born at home, or born abroad, even their nakedness thou shalt not uncover. Leviticus 18:9

The reason judeochristians spend SO much time and energy trying to find just one instance where the House of Israel disobeyed or disregarded Deuteronomy 23:2 is that if they can succeed in proving to themselves that a mamzer is not the offspring of mixed race parents, or that the House of Israel merely disregarded this aspect of God's Law, or if they can find just one precedent for whatever reason for setting aside God's Law, then they're home free to: 

1. Proclaim from the rooftops that God never had any right to make an everlasting racial covenant with Abraham through Jacob.
2. Condemn anyone who would dare to mention that God DID make an everlasting covenant with the posterity [read: seed] of Jacob, as racists, hateful, Nazis, neo-Nazis, and KKK.
3. Disassemble each and every last tittle of God's Law.

Thus their wildest dreams would come true if only they could prove that Rehoboam, who God made King of Judah, was the son of a racial Ammonitess:

1Kings 14:21 And Rehoboam the son of Solomon reigned in Judah. Rehoboam was forty and one years old when he began to reign, and he reigned seventeen years in Jerusalem, the city which the LORD did choose out of all the tribes of Israel, to put his name there. And his mother's name was Naamah an Ammonitess.

1Kings 14:31 And Rehoboam slept with his fathers, and was buried with his fathers in the city of David. And his mother's name was Naamah an Ammonitess. And Abijam his son reigned in his stead.

2 Chronicles 12:13 So king Rehoboam strengthened himself in Jerusalem, and reigned: for Rehoboam was one and forty years old when he began to reign, and he reigned seventeen years in Jerusalem, the city which the LORD had chosen out of all the tribes of Israel, to put his name there. And his mother's name was Naamah an Ammonitess.

If Rehoboam's mother Naamah was a racial Ammonitess, rather than an Israelite living in Ammon, then Rehoboam would have three major problems

1. He would have been a mamzer who can't enter the congregation of the LORD forever.
2. He would have been a descendant of Ammonites who also can't enter the congregation of the LORD forever.
3. He would have been the offspring of incest between Lot and his daughter who bore Ammon.

Those who proclaim God's Law dead, null and void, fulfilled, nailed to a cross, or written on their hearts shall not prevail, nor will they ever receive remission from their sins.  God's Law, the Torah, the Pentateuch, the Law of Moses, or the first five books of the Holy Bible, shall prevail, which means that God would not have permitted the son of a racial Ammonitess to be King of Judah.

The following is an example of the lengths to which judeochristians will go to discredit God's Law:

        Transferring David's Throne To The North: Now, Adonijah was David's legitimate legal son and heir under GOD.    Whereas, Solomon was the seed of David given unto Bathsheba the legal legitimate wife of Uriah the Hittite.   That is, as the wife of Uriah, Bathsheba engaged in whoredom with David; therefore, the first child so conceived was smitten by GOD and died (II Samuel 11:1-5; 12:1-18).   Meanwhile, David had Uriah sent to the front lines of a conflict that Uriah would be killed.   Thus, under GOD'S Marriage Laws, after Uriah's death David could now legally take Bathsheba as his concubine, a pseudo wife; but, Solomon, the second child conceived by David and Bathsheba, although the seed of David, was the legal son and heir of Bathsheba's dead husband, Uriah the Hittite of the lineage of Heth, son of the cursed Canaan (Ruth 4:10; Genesis 38:8-9; II Samuel 11:6-27, 12:24-25).   Therefore, Solomon was legally, under GOD, of the lineage of the cursed Canaan.   Yes, Solomon and Solomon's heirs are Canaanites!

          So, when David gave his throne unto Solomon (Jeremiah 22:2), David actually gave his world throne unto the Canaanites.   Thus, because of humanity's disobedience, GOD had set up the accursed lineage of Canaan as world rulers under Satan.   The Book of Revelation describes it as the throne over the Sixth Kingdom (Revelation 17:10-11).   And, the throne of Solomon's Kingdom, called "Judah," reigned over this world until agents took GOD'S Holy Ark captive in 1985 AD (Genesis 49:1,10; Zechariah 5:4).    That's when GOD began withdrawing His powers from Jewry.

We know from 2 Samuel 12:24 that Bath-sheba was David's wife, not concubine:

Even had she been a concubine, it's incorrect to argue that Rehoboam had any connection whatsoever, biological or legal, to his mother's prior "husband".  It's also incorrect to argue that Israelites would ever have recognized this illegal relationship between Bathsheba an Israelite and Uriah a Hittite as a "marriage", particularly when any offspring they might have had would have been a mamzer who could not enter into the congregation of the LORD, even to the tenth generation.

The sin which divided the House of Israel from the House of Judah was not David's legal marriage to Bath-sheba, but Solomon's illegal and sinful marriages to foreign women:

And King Solomon loved many foreign women, even the daughter of Pharaoh, Moabites, Ammonites, Edomites, Sidonians, Hittites; 1 Kings 11:1

The following makes a good point about the sins of Judah, his miscegenation with Canaanite women, and his polluted lineage, but it incorrectly presumes that a mamzer is a "fatherless" child, and that Judah violated God's laws regarding Tamar:

          Judah's Disobedience: Much earlier, Judah of the tribe of Israel was instrumental in selling his brother, Joseph, into slavery (Genesis 37:26-28).   Judah, like Esau, also married a Canaanitish woman, symbolic of the harlot, in direct disregard of both Abraham and Isaac's admonitions (Genesis 38:1-2; 24:3,37; 26:34-35; 28:1,6).   Judah also went into Tamar, his daughter-in-law (Genesis 38:13-30).   This was an obvious violation of both GOD'S laws and man's laws ... the twins begotten thereby were termed "mamzer" (fatherless).   Therefore, legally, under GOD, Judah had no legitimate sons and heirs (Malachi 2:11-12).

          Subsequently, the name and title "Judah" was bestowed upon this disobedient world.   Thus, everyone born into this world is a Judahite much the same as a person is an automatic citizen of their birth nation.   However, those openly claiming to be Solomon's children and Judah also falsely claim to be Israel while declaring all others excepting themselves to be "g�y."

By disguising herself as a harlot, Tamar tricked Judah into impregnating her, but if there was any error in judgment by Judah, it was his failure to follow thru with "And Judah said, Bring her out and let her be burned",Genesis 38:24 when he found out who she was and what she had done.  Judah's real sin was marrying Canaanite women:

Judah hath dealt treacherously, and an abomination is committed in Israel and in Jerusalem; for Judah hath profaned the holiness of the LORD which he loved, and hath married the daughter of a foreign god.  The LORD will cut off the man that doeth this, the master and the scholar, out of the tabernacles of Jacob, and him that offereth an offering unto the LORD of hosts. Malachi 2:11-12

1Ki 12:1 And Rehoboam went to Shechem: for all Israel were come to Shechem to make him king.

1Ki 12:2 And it came to pass, when Jeroboam the son of Nebat, who was yet in Egypt, heard of it, (for he was fled from the presence of king Solomon, and Jeroboam dwelt in Egypt;)

1Ki 12:3 That they sent and called him. And Jeroboam and all the congregation of Israel came, and spoke unto Rehoboam, saying,

1Ki 12:4 Thy father made our yoke grievous: now therefore make thou the grievous service of thy father, and his heavy yoke which he put upon us, lighter, and we will serve thee.

1Ki 12:5 And he said unto them, Depart yet for three days, then come again to me. And the people departed.

1Ki 12:6 And king Rehoboam consulted with the old men, that stood before Solomon his father while he yet lived, and said, How do ye advise that I may answer this people?

1Ki 12:7 And they spoke unto him, saying, If thou wilt be a servant unto this people this day, and wilt serve them, and answer them, and speak good words to them, then they will be thy servants forever.

1Ki 12:8 But he forsook the counsel of the old men, which they had given him, and consulted with the young men that were grown up with him, and which stood before him:

1Ki 12:9 And he said unto them, What counsel give ye that we may answer this people, who have spoken to me, saying, Make the yoke which thy father did put upon us lighter?

1Ki 12:10 And the young men that were grown up with him spoke unto him, saying, Thus shalt thou speak unto this people that spoke unto thee, saying, Thy father made our yoke heavy, but make thou it lighter unto us; thus shalt thou say unto them, My little finger shall be thicker than my father's loins.

1Ki 12:21 And when Rehoboam was come to Jerusalem, he assembled all the house of Judah, with the tribe of Benjamin, a hundred and fourscore thousand chosen men, which were warriors, to fight against the house of Israel, to bring the kingdom again to Rehoboam the son of Solomon.

1Ki 14:29 Now the rest of the acts of Rehoboam, and all that he did, are they not written in the book of the chronicles of the kings of Judah?

1Ki 14:30 And there was war between Rehoboam and Jeroboam all their days.

1Ki 14:31 And Rehoboam slept with his fathers, and was buried with his fathers in the city of David. And his mother's name was Naamah an Ammonitess. And Abijam his son reigned in his stead.