This has been an interesting discussion. I appreciate the Bible verses which make it clear. Discernment between good and evil is a matter of maturity in life, the result of continual exercise to be obedient to God's word.
Hebrews 5:13 Anyone who lives on milk, being still an infant, is not acquainted with the teaching about righteousness. 14 But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil. (NIV)
Scripture foretells Messiach, who's able to know, understand, and choose rightly, even from a youth. Isaiah 7:14 Therefore the Lord Himself will give you a sign: Behold, the virgin shall conceive and bear a Son, and shall call His name Immanuel. 15 Curds and honey He shall eat, that He may know to refuse the evil and choose the good. (NKJV)
One type of Messiach is the enthroned King of Israel. I Kings 3:9 Give your servant therefore an understanding mind to govern your people, that I may discern between good and evil, for who is able to govern this your great people? (ESV)
Children, on the other hand, are unable to discern: "Moreover, your little ones who you said would become a prey, and your sons, who this day have no knowledge of good or evil, shall enter there, and I will give it to them and they shall possess it." Deut 1:39
But I don't think God wants us to remain children. Hebrews 5 is clear on this: go on to maturity. Philippians 2:8 shows us the Master, going before: "And being found in appearance as a man, he humbled himself by becoming obedient to death-- even death on a cross! " (NIV)