For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
I would appreciate a response from a blessed single Mom.
I believe the question refers to Joseph and Mary.
The one thing the initial response to this question left out is God. Yes God can turn any sin into a blessing but there is a price to pay. And that price is repentance. 2 Cor 7:10 tells us that only Godly sorrow works repentance to salvation. One may have received Jesus as savior but reject him as Lord. True salvation is all inclusive. If you're saved in your spirit, that same repentance will filter to your soul (mind, will and emotions).
God may make a mistake a blessing, but he may do it through the child, if he is willing to repent for his own sins. If the person who offended God is not willing to make repentance to God the priority over the action, God cannot bless. Jesus said in Matt 10:37 he who loves father, mother, son or daughter more than me is not worthy of me.
Beware - Worldly repentance (Oh, I got caught) leads only to death.
"Make a mistake a blessing"?
The question, boiled down, is 'How can a sinful act lead to a blessing'?
Fighting is sinful. Killing is sinful. ALL THE TIME!! Don't give me that holy war nonsense. Don't tell me about God telling His chosen people to kill all the inhabitants of a society. God told His sinful people to kill some other sinful people. The only righteous one in that exchange is God.
That said:
War is sinful. There's nothing righteous about one child killing another for any reason. God's children learned to kill on their own, we weren't trained by anyone. Our hearts are desperately wicked (Jer 17:9).
Losing in war is horrible. That makes winning a war a blessing. That sinful institution can turn out to be a blessing. Are we blessed to have killed our brothers and sisters? No! Is destruction of property a good thing? No, of course not!! Is saving your own property a good thing? Is preserving your own way of life, culture, freedom and resources a good thing? Of course it is! You're BLESSED in those outcomes!!
If a woman is raped and she lives through it, she was blessed to live through that horrible episode. My community survived through over 200 years of legalized slavery in the United States. To survive that awful sinful institution is a blessing.
This is the thing to remember when these ridiculous, judgmental thoughts pop into your head: ONLY SINNERS GIVE BIRTH TO CHILDREN. And having a child is a blessing.