The true Christian has a thorough work of grace and sanctification wrought in his heart. Regeneration is a whole change. The old things are done away, while all things become new. M. Meade writes:
Here are two questions of very great importance which we should every one of us put to ourselves: “What am I?” and “Where am I?” Am I a child of God or not? Am I sincere in religion, or am I only a hypocrite under a profession? Am I yet in a natural state, or in a state of grace? Am I yet in the old root, in old Adam, or am I in the Root, Christ Jesus? Am I in the covenant of works that ministers only wrath and death, or am I in the covenant of grace that ministers life and peace? I press this upon you that are professors, because many rest in a notion of godliness and an outward show of religion, and yet remain in their natural condition. Many are hearers of the Word and not doers of it, and so deceive their own souls (James 1:22). He that slights the ordinances cannot be a true Christian, but yet it is possible a man may own them and yet be no true Christian.
Errors in the first foundation are very dangerous. If we be not right in the main, the fundamental work, if the foundation be not laid in grace in the heart, all our following profession comes to nothing. The house built upon a sandy foundation, though it may stand for a while, yet when the floods come and the winds blow and beat upon it, great will be the fall of it. There are many things like grace that are not grace.
Now it is the likeness of things that deceives. Many take gifts for grace; common knowledge for saving knowledge; whereas a man may have great gifts and no grace, great knowledge and yet not know Jesus Christ. Some take common faith for saving; whereas a man may believe all the truths of the gospel, all the promises, all the threatenings, all the articles of the creed to be true, and yet perish for want of saving faith. Some take morality and restraining grace for renewing grace; whereas it is common to have sin much restrained where the heart is not at all renewed. Some are deceived with a half-work, making many mermaid Christians, or like Nebuchadnezzar’s image, head of gold and feet of clay. Endless are the delusions that Satan fastens upon souls for want of this self-search. Satan will try us at one time or other. He will winnow us and sift us to the bottom, and if we now rest in a groundless confidence, it will then end in a comfortless despair. Nay, God Himself will search and try us, at the Day of Judgment especially, and who can abide that trial, that never tries his own heart?
Whatsoever a man’s state be, whether he be altogether a Christian or not, yet it is good to examine his own heart. If he finds his heart good, his principles right and sound, this will be a matter of rejoicing. If he finds his heart rotten, his principles false and unsound, the discovery may be in order to a renewing. If a man have a disease upon him and know it, he may send to the physician in time, but what a sad vexation it will be not to see the disease till it is past cure! So for a man to be graceless and not see till it be too late, to think himself a Christian when he is not; that he is in the right way to heaven when he is in the ready way to hell, and yet not know it till a death bed or a judgment day confute his confidence, this is the most irrecoverable misery. These are the grounds upon which I press this duty of examining our state. Oh, that God would help us in doing this necessary duty! (“Almost a Christian”, 1661)