Psa. 53:3 The wicked are estranged from the womb: they go astray as soon as they be born, speaking lies.
4 Their poison is like the poison of a serpent: they are like the deaf adder that stoppeth her ear;
5 Which will not hearken to the voice of charmers, charming never so wisely.
In this passage we see a pattern of making a statement and then making a second statement that adds to or further clarifies the first statement. It says they go astray after they are born, not while in the womb. It says "from" the womb, meaning once they "come from" the womb - in other words, after they are born.
Ps 51:5 Behold, I was shapen in iniquity; and in sin did my mother conceive me.
Shapen in iniquity - Shapen is the word chuwl which means to writh, dance, twist, to be born, to be brought forth. Iniquity is the word avon which can mean 'punishment for iniquity' or 'consequence for iniquity'. Notice the word "sin" is used in the verse. David could have used the word sin - chet - but used avon instead.
Furthermore, in the second half of the verse, you must apply the verb to the subject consistently. If you apply "sin" to David, then you must also apply "conceived" to David in a consistent manner and that would mean that David conceived himself which is ridiculous.
So the verse could literally be translated - "I was brought forth under the punishment for sin; my mother was a sinner when she conceived me. "
The verse shows the total hopelessness of David. He was born inheriting death, and he couldn't even rely on a righteous inheritance from his parents to save him. This makes MUCH more sense of the verse considering the poetic prose nature of the passage. It is the same style as chapter 53 - a statement and then another statement that underscores or expounds on the first.
Job. 14:4 Who can bring a clean thing out of an unclean? not one.
Psa 139:13 For You formed my inward parts; You wove me in my mother's womb.
Psa 22:10 I was cast upon thee from the womb: thou [art] my God from my mother's belly.
Job 15:14 What is man, that he should be clean? and he which is born of a woman, that he should be righteous?
Gal 4:4 But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law,
5 To redeem them that were under the law, that we might receive the adoption of sons.
Jesus was also the son of man born of a sinful woman. If you say he wasn't, then you say he is disqualified to be our redeemer.
Every parent knows from observational experience that children ALWAYS require discipline to restrain evil that naturally flows from their hearts as soon as they are able to express themselves.
You must have seriously hated your children to characterize them in this way. I have a daughter who is nearly 2 and she requires only minimal disciple. She is a true joy. I have observed she has a genuinely good and loving heart. She has such pure faith in those around her and always thinks good of those around her. In fact, I have learned so much about what pure, undefiled, unselfish love is from her. In her I have observed true empathy and altruism - something I find completely lacking in adults.
Solomon says this is "bound in the heart" of a child and discipline is necessary to drive it from them. David says that they were conceived "in sin."
Why is it that children need to be trained to do what is right but naturally do what is evil without any training, if they are not evil by nature from birth?
If you meet a child's needs, they tend to not behave in a depraved manner. The Bible says spare the rod spoil the child, it does not say too much love, affection, and service will spoil the child. Failure to discipline wrong behavior will spoil a child, not an over abundance of meeting their needs. I suggest that if your kids came out little sinners it is because you failed as a parent to meet their needs.
Hbr 2:15 And deliver them who through fear of death were all their lifetime subject to bondage.
It's a fear of not having needs met that enslaves people to sin and selfishness.
Eph 6:4 And, ye fathers, provoke not your children to wrath: but bring them up in the nurture and admonition of the Lord.
Col 3:21 Fathers, provoke not your children [to anger], lest they be discouraged.