"How May I Know Whether I Have the Spirit of Christ or Not?"

It pleased the Father, that in him should all fulness dwell. Colossians 1:19.

The religion of nature is the religion of pride. Pride is of the devil. Pride works by a lie, and keeps the soul in unbelief of the truth. Hence, we naturally think some change in us, some good done by us, causes God to be our Father, and we consider ourselves as his very good children. This notion obtains in the mind of many, and is the cause of their rejecting the everlasting covenant of the three-one Jehovah, and denying the covenant relations and transactions of God the Father, Son, and Holy Ghost. They are so filled with themselves, with their Stuff of inherent righteousness, free-will, moral agency, and one knows not what unscriptural jargon, that they see not all fulness in Jesus, where it pleased the Father it should dwell. Lord! empty us of all self-fulness, that we may receive out of thy fulness. The Father, by covenant love, took on him that near and dear relation to all his chosen, when his eternal, co-equal Son, covenanted to become man, to sustain the curse for man, to satisfy justice, and obtain every blessing for sinners: this pleased the Father. And as man had lost all holiness, happiness, and blessedness by the first Adam, and was quite empty of all good, all fulness is treasured up and dwells in the second Adam, the Lord from heaven: this also pleased the Father. The Father of whom? “If any man have not the Spirit of Christ, he is none of his.”....Romans 8:9. Here the covenant office of the blessed Spirit is engaged, to convince us of sin, to empty us of self-sufficiency, and to shew us the fullness that dwells in Jesus for us. Hence, here is a plain answer to that question, How may I know whether I have the Spirit of Christ or not? Do you see yourself stripped of all righteousness, emptied of all good, prone to every evil? This is the teaching of the Spirit. Do you see the fulness that dwells in that glorious Man, Christ Jesus? that you must receive pardon of sin, justifying righteousness; adoption, to be a child of God, by faith in him; sanctification, and eternal redemption out of his fulness? Are you pleased at this? Are you satisfied to come, day after day, as a self-emptied sinner, hungry and thirsty, to receive out of his fulness? Can you say so? Then, you have the Spirit of God; for what pleased the Father, pleases you. O! rejoice in this. You may say with the apostles and all saints, “Truly our fellowship is with the Father, and with his Son Jesus Christ.” (1 John 1:3.)

Lord, pull our haughty spirits down,
Our empty hearts renew;
O! make us fall, and see, and own
All fulness in thy Son.

Spirit of grace! lead us to Christ,
As to our fountain head,
Out of his fulness to be blest
With life and living bread.

- William Mason, A Spiritual Treasury For The Children of God, Volume 2, February 26

(emphasis mine)