Can anyone help me find the passage which says something to the effect that anything which begins unlawfully or in sin, remains unlawful?
Could it be either of these two verses:
“But children of adulterers will not come to maturity, and the offspring of an unlawful union will perish.” [Wisdom 3:16]
“For children born of unlawful unions are witnesses of evil against their parents when God examines them.” [Wisdom 4:6]
Ezekiel 18:20 The soul who sins shall die. The son shall not bear the guilt of the father, nor the father bear the guilt of the son. The righteousness of the righteous shall be upon himself, and the wickedness of the wicked shall be upon himself.
Wisdom seems to point out that as a general rule children born of adulterers do not usually fare/turn out as well as children born in wedlock. Through no fault of their own, they face difficult obstacles in life.
God shows Peter that not all “unlawful” things in the Old Covenant are unlawful things in the New Covenant:
Acts 10:28 And he said to them, "You yourselves know how unlawful it is for a man who is a Jew to associate with a foreigner or to visit him; and yet God has shown me that I should not call any man unholy or unclean.