To be "sanctified" is to be made a partaker of that holiness, without which no man shall see the Lord; to be made a new creature; to "put on the new man, which after God is created in righteousness and true holiness;" in a word, to be "made a partaker of the divine nature," and thus have the holiness of God breathed into and communicated to the soul. Without this inward sanctification, none can enter the gates of heaven.
To be made meet, therefore, for the heavenly inheritance, you must have a heavenly heart and a praising, adoring, loving spirit; you must delight yourself in the Lord as being so holy and yet so gracious, so pure and yet so loving, so bright and glorious and yet so condescending and sympathising. Now this meetness for the holiness, happiness, and employments of heaven is communicated at regeneration, in which the new man of grace, though weak, is still perfect.
Look at the thief upon the cross: what an instance is he how the Spirit of God can in a moment make a man meet for heaven! Here was a vile malefactor, whose life had been spent in robbery and murder, brought at last to suffer the just punishment of his crimes; and as we are told that "they which were crucified with him reviled him," we have reason to believe that at first he joined his brother malefactor in blaspheming the Redeemer.
But sovereign grace, and what but sovereign grace? touched his heart, brought him to see and feel what he was as a ruined sinner, opened his eyes to view the Son of God bleeding before him, raised up faith in his soul to believe in his name, and created a spirit of prayer that the Lord of heaven and earth would remember him when he came into his kingdom—perhaps the greatest act of faith we have recorded in all Scripture, almost equal if not superior to the faith of Abraham when he offered up Isaac on the altar. The dying Redeemer heard and answered his cry, and said to him, "To-day shalt thou be with me in paradise." Spirit and life accompanied the words, and raised up at once in his soul a meetness for the inheritance, and before the shades of night fell his happy spirit passed into paradise, where he is now singing the praises of God and of the Lamb.
Many a poor child of God has gone on almost to his last hours on earth without a manifestation of pardoning love and the application of atoning blood; but he has not been suffered to die without the Holy Ghost revealing salvation to his soul, and attuning his heart to sing the immortal anthem of the glorified spirits before the throne.