I already answered your question, but as usual I need to repeat my answer many time before the penny7 drops for you. I made it clear that nobody apart from God and the saved person know for sure. The rest of the Church members can't know for sure.
According to your theory, Judas Iscariot was a genuine believer. But we found out that he is actually a Devil. So, why should I blindly believe that every professing Christian is a genuine born again believer. 
		
		
	 
No what I said has nothing to do with Judas. Calvin’s doctrine of total depravity comes from gnostic heresy that was literally refuted by Iranaeus in 170AD in his writing Adversus Haereses which was literally written to refute Gnosticism. 
1. Man has received the 
knowledge of good and 
evil. It is 
good to 
obey God, and to 
believe in Him, and to keep His commandment, and this is the life of man; as not to 
obey God is 
evil, and this is his death. Since 
God, therefore, gave [to man] such mental power (magnanimitatem) man 
knew both the good of 
obedience and the 
evil of disobedience, that the eye of the 
mind, receiving experience of both, may with judgment make choice of the better things; and that he may never become indolent or neglectful of God's command; and learning by experience that it is an 
evil thing which deprives him of life, that is, disobedience to 
God, may never attempt it at all, but that, 
knowing that what preserves his life, namely, 
obedience to 
God, is 
good, he may diligently keep it with all earnestness. Wherefore he has also had a twofold experience, possessing 
knowledge of both kinds, that with discipline he may make choice of the better things. But how, if he had no 
knowledge of the contrary, could he have had instruction in that which is 
good? For there is thus a surer and an undoubted comprehension of matters submitted to us than the mere surmise arising from an opinion regarding them. For just as the tongue receives experience of sweet and bitter by means of tasting, and the eye discriminates between black and white by means of vision, and the ear recognises the distinctions of sounds by hearing; so also does the 
mind, receiving through the experience of both the 
knowledgeof what is 
good, become more tenacious of its preservation, by acting in 
obedience to God: in the first place, casting away, by means of repentance, disobedience, as being something disagreeable and nauseous; and afterwards coming to understand what it really is, that it is contrary to goodness and sweetness, so that the mind may never even attempt to taste disobedience to 
God. But if any one do shun the 
knowledge of both these kinds of things, and the twofold perception of 
knowledge, he unawares divests himself of the character of a 
human being.
2. How, then, shall he be a 
God, who has not as yet been made a man? Or how can he be perfect who was but lately created? How, again, can he be 
immortal, who in his mortal nature did not 
obey his Maker? For it must be that you, at the outset, should hold the rank of a 
man, and then afterwards partake of the 
glory of 
God. For you did not make 
God, but God you. If, then, you are God's workmanship, await the hand of your Maker which creates everything in due time; in due time as far as you are concerned, whose creation is being carried out. Offer to Him your heart in a soft and tractable state, and preserve the form in which the Creator has fashioned you, having moisture in yourself, lest, by becoming hardened, you lose the impressions of His fingers. But by preserving the framework you shall ascend to that which is perfect, for the moist clay which is in you is hidden [there] by the workmanship of 
God. His hand fashioned your substance; He will cover you over [too] within and without with pure gold and silver, and He will adorn you to such a degree, that even the King Himself shall have pleasure in your beauty. But if you, being obstinately hardened, reject the operation of His skill, and show yourself ungrateful towards Him, because you were created a [mere] man, by becoming thus ungrateful to 
God, you have at once lost both His workmanship and life. For creation is an attribute of the goodness of God but to be created is that of 
human nature. If then, you shall deliver up to Him what is yours, that is, 
faith towards Him and subjection, you shall receive His handiwork, and shall be a perfect work of 
God.
3. If, however, you will not 
believe in Him, and will flee from His hands, the 
cause of imperfection shall be in you who did not 
obey, but not in Him who called [you]. For He commissioned [messengers] to call people to the marriage, but they who did not 
obeyHim deprived themselves of the royal supper. 
Matthew 22:3, etc. The skill of 
God, therefore, is not defective, for He has power of the stones to raise up children to 
Abraham; 
Matthew 3:9but the man who does not obtain it is the 
causeto himself of his own imperfection. Nor, [in like manner], does the light fail because of those who have blinded themselves; but while it remains the same as ever, those who are [thus] blinded are involved in darkness through their own fault. The light does never enslave any one by necessity; nor, again, does God exercise compulsion upon any one unwilling to accept the exercise of His skill. Those 
persons, therefore, who have 
apostatized from the light given by the 
Father, and transgressed the law of liberty, have done so through their own fault, since they have been created free agents, and possessed of power over themselves.
4. But 
God, foreknowing all things, prepared fit habitations for both, kindly conferring that light which they desire on those who seek after the light of incorruption, and resort to it; but for the despisers and mockers who avoid and turn themselves away from this light, and who do, as it were, blind themselves, He has prepared darkness suitable to 
persons who oppose the light, and He has inflicted an appropriate punishment upon those who try to avoid being subject to Him. Submission to 
God is 
eternal rest, so that they who shun the light have a place worthy of their flight; and those who fly from 
eternal rest, have a habitation in accordance with their fleeing. Now, since all 
good things are with 
God, they who by their own determination fly from 
God, do defraud themselves of all 
good things; and having been [thus] defrauded of all 
good things with respect to 
God, they shall consequently fall under the just judgment of 
God. For those 
persons who shun rest shall 
justly incur punishment, and those who avoid the light shall 
justly dwell in darkness. For as in the case of this temporal light, those who shun it do deliver themselves over to darkness, so that they do themselves become the 
cause to themselves that they are destitute of light, and do inhabit darkness; and, as I have already observed, the light is not the 
cause of such an [unhappy] condition of 
existence to them; so those who fly from the 
eternal light of 
God, which contains in itself all 
good things, are themselves the 
cause to themselves of their inhabiting 
eternal darkness, destitute of all 
good things, having become to themselves the 
cause of [their consignment to] an abode of that nature.
St Iranaeus 170AD Adversus Haereses Book 4 Chapter 39