Supposed contradiction and verses:
How many children did Michal, the daughter of Saul have?
None:
2 Samuel 6:23
Therefore Michal the daughter of Saul had no child unto the day of her death.
Five:
2 Samuel 21:8
But the king took the two sons of Rizpah the daughter of Aiah, whom she bare unto Saul, Armoni and Mephibosheth; and the five sons of Michal the daughter of Saul, whom she brought up for Adriel the son of Barzillai the Meholathite:
Answer:
David had sent Michal away and while gone, she had given birth to five sons while with Adriel as we see in this verse. David asks for her return here:
2 Samuel 3:14
And David sent messengers to Ishbosheth Saul’s son, saying, Deliver me my wife Michal, which I espoused to me for an hundred foreskins of the Philistines.
After she returned to David, God closed her womb due to the way she acted towards David as he celebrated the ark of the LORD returning. Please read 2 Samuel 6:16-23. When the writer says she had no child he simply is speaking from the time she is reunited with David, as he mentions the five later in chapter 21. 2nd Samuel is not chronological in this area, 2 Samuel 21:8 is a thought looking back before the events of 6:23. The atheist has taken the 23rd verse out of context, as we see, there is no contradiction