God Gives the Evidence of the Spirit of God in the Believer

Someone who is born again naturally without trying displays the fruit of God's Spirit. Next time someone says to you; "you don't know their heart", remind them of God's own words. Yes, only God knows the heart and God speaks to those who belong to Him so they do not fall into the trap of enabling and accepting a rebellious soul who may not be saved.

 
Matthew 7:15-20
You Will Know Them by Their Fruits
15 “Beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ravenous wolves. 16 You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles? 17 Even so, every good tree bears good fruit, but a bad tree bears bad fruit. 18 A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. 19 Every tree that does not bear good fruit is cut down and thrown into the fire. 20 Therefore by their fruits you will know them."

Galatians 5:22-23 "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law".

If someone consistently disrespects the Word of God and others, we should challenge them to ask God if they are saved because the fruit looks bad. 

Matthew 7:21-23 "21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. 22 On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ 23 And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’"