Dear friends, there are many that profess and confess that they know God, our Lord and Savior Jesus Christ, but in works they deny Him, (Titus 1:16) you can say anything you want and profess it to the whole world but if your walk does not line up with the Word of God, ye are yet in your sins. Jesus said in John 14:15-21 If ye love me, keep my commandments.  And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;  Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.  I will not leave you comfortless: I will come to you.  Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also.  At that day ye shall know that I am in my Father, and ye in me, and I in you.  He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father, and I will love him, and will manifest myself to him.
You see, if they really knew Him, they would flee to Him, (His Word), with great cryings and desires to be so obedient to Him their God, they would have a filial fear of the slightest disobedience and a hatred of the flesh that is tainted by sin, transgression against the commands of God. Being birth by the Spirit and power of the Almighty God is much different than making a decision for Christ, or accepting him as your personal savior. When a soul is born from above, God puts a love for Him into them and gives them the gift of faith to trust Him for all, creates in them a desire to study, seek, hunger and thirst after righteousness. 1 John 2:3-6 And hereby we do know that we know him, if we keep his commandments.  He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.  But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.  He that saith he abideth in him ought himself also so to walk, even as he walked.
Now dear brethren, you cannot use this knowledge to judge any individual you may know but use it to judge yourselves and to make your election and calling sure, II Peter 1:10. Let us spend our time, perfecting ourselves in the knowledge of our Lord, then preaching that to the world; it will be precious to the sensible sinners and witness against the enemies of God on that Great Day of the Lord.