1 John 3:6 (ESV)
No one who abides in him keeps on sinning; no one who keeps on sinning has either seen him or known him.
1 John 2:3–6 (ESV)
And by this we know that we have come to know him, if we keep his commandments. Whoever says “I know him” but does not keep his commandments is a liar, and the truth is not in him, but whoever keeps his word, in him truly the love of God is perfected. By this we may know that we are in him: whoever says he abides in Him ought to walk in the same way in which He walked.
1 Corinthians 2:12-14
Now we have received not sthe spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God. And we impart this tin words not taught by human wisdom but taught by the Spirit, uinterpreting spiritual truths to those who are spiritual. The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned.
John 14:15-17 & 26
If you love me, you will keep my commandments. And I will ask the Father, and he will give you another Helper,to be with you forever, even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you. But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you.
John 10:4–5 (ESV)
When he has brought out all his own, he goes before them, and the sheep follow him, for they know his voice. A stranger they will not follow, but they will flee from him, for they do not know the voice of strangers.
Matthew 7:21–22 (ESV)
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. 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?'
-adapted from http://jesusrulzme.blogspot.com/2008/04/true-or-false-conversion.html