Men must resolve to be determined by Scripture in this matter of their interest in Christ. The Spirit speaking in the Scripture is judge of all controversies’ – To the law and to the testimony; if they speak not according to this word, it is because there is no light in them’ (Isa. 8: 20) – and of this also, whether a man be savingly in covenant with God or not. Therefore do not mock God whilst you seem to search after such a thing. If we prove from Scripture, which is the uncontroverted rule, that you are gracious, and have made a covenant savingly with God, then resolve to grant so much, and to acquiesce in it. . . .
[A]lthough the matter of a man’s interest in Christ be of so great importance, and the way to attain to the knowledge of it so plainly held forth in the Scriptures, yet there be but few who reach the distinct knowledge of it. And that this may not discourage any person from attempting it, I shall hint some few reasons why so few come to the clear knowledge of it. . . .
The first thing which hinders many from the knowledge of their interest in Christ is their ignorance of some special principles of religion; as,
That it was free love in God’s bosom, and nothing in man, that moved Him to send a Savior to perfect the work of redemption (John 3: 16). . . .
They are ignorant how that love effectually discovers itself to a man’s heart, so as he has ground to lay claim to it. . . .
Many are also ignorant of this, that God alone is the hope of His people; He is called ‘the hope of Israel.’ (Jer. 14: 8.) Although inherent qualifications are evidences of it, yet the staying of the heart upon Him, as a full blessing and satisfying portion, is faith. . . .
They are ignorant of the different degrees and ways of that work of the law, by which God ordinarily dealeth with men, and of the different ways in which the Lord bringeth people at first to Christ. . . .
There is one thing or other wherein their heart, in some respect, does condemn them, as dealing deceitfully and guilefully with God. It is not to be expected that those can come to clearness about their interest, whose heart does condemn them for 
keeping up some known transgressions against the Lord, which they will not let go, neither are using the means which they know to be appointed by God for delivering them from it. . . .
[Another hindrance] is a spirit of sloth and careless negligence. They complain that they know not whether they are in Christ or not; but as few take pains to be in Him, so few take pains to try if they be in Him. It is a work and business which cannot be done sleeping: ‘Examine yourselves whether ye be in the faith; prove your own selves: know ye not your own selves.’ (2 Cor. 13: 5.) The several words used here, namely, Examine, prove, know–intimate that there is a labor in it: Diligence must be used to make our ‘calling and election sure. . . .’ (2 Peter 1: 10)
Be ashamed, you who spend so much time in reading of romances, in adorning your persons, in hawking and hunting, in consulting the law concerning your outward state in the world, and it may, be in worse things than these; – Be ashamed, you that spend so little time in the search of this, whether ye be an heir of glory or note whether you be in the way that leadeth to heaven, or that way which will land you in darkness for ever? You who judge this below you, and unworthy of your pains, any part or minute of your time, it is probable, in God’s account, you have judged yourselves unworthy of everlasting life, so that you shall have no lot with God’s people in this matter.
Written by Bishop J. C. Ryle:
Men often complain they are in darkness concerning their position in Christ and this often because they have not believed and given credit to the record which God has given of the Son. As long as people neglect these things, they can hardly come to the knowledge of the gracious state. William Guthrie guides us through some issues that hinder our understanding of these matters:
Samuel at Gilgal 