If it's not your position, what is your understanding of what that term means?
If this helps, this is what I believe happens to someone after they believe.
Eph 1:13 "In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,"
Ok, he heard the gospel, he believed, after that he is sealed with the Holy Spirit. The washing away of sin and the sealing of the Holy Spirit sanctifies him permanently until the first resurrection.
Eph 1:14 "Which is the earnest of our inheritance
until the redemption of the purchased possession, unto the praise of his glory."
He has been led by the Spirit,
Rom 8:14 For as many as are led by the Spirit of God, they are the sons of God.
He has been testified to by the Spirit,
Rom 8:16 The Spirit itself beareth witness with our spirit, that we are the children of God:
He has been taught by the Spirit,
John 14:17 "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."
And he has been given the power to become a son of God
John 1:12 "But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name"
I believe the sanctification stays the same, neither increasing or decreasing.