But of Him you are in Christ Jesus, who became for us wisdom from God—and righteousness and sanctification and redemption— – 1 Corinthians 1:30

We are saved in Christ. We are complete in Him. We are sanctified in Christ Jesus: “And He is made of God unto us wisdom, righteousness, sanctification, and redemption.” Christ is all, not in my justification only, but in my sanctification too. He is all, not only in the first steps of my faith, but in the last. “He is Alpha and Omega; He is the beginning and the ending, saith the Lord.” There is no point between the gates of hell and the gates of heaven where a believer shall have to say, “Christ fails me here, and I must rely upon my own endeavors. From the dunghill of our corruption up to the throne of our perfection there is no point left to hazard, or set aside for us to supply; our salvation has Christ to begin with, Christ to go on with, and Christ to finish with, and that in all points, at all times, for every man of woman born that ever shall be saved. There is no point in which the creature comes in to claim merit, or to bring strength, or to make up for that which was lacking. “Christ is all, and in all.” The saints are “perfect in Christ Jesus.” He said, “it is finished,” and finished it is. He is not the author of our faith only, but the finisher of it too. He is all in all, and man is nothing at all.

This is a truth which every believer has recognised. There are a great many differences among believers, but there is no difference as to this essential point. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1006.cfm

Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved. – Acts 4:12

Christ is all in all. – Colossians 3:11

There are many who, unconsciously to themselves, think Jesus Christ to be much, but yet they do not understand that He is all in all. I allude to many seeking souls, who say, “I would put my trust in Jesus this morning, but I do not feel as I ought.” I see, thou thinkest that there is at least a little of thy feeling to be added to the Savior’s work ere it can avail for thee. “But I am not as penitent as I should be, and, therefore, I cannot rest in Jesus.” I see, thy penitence is to add the topstone to the Savior’s yet unfinished work. Perhaps it is one of the hardest works in the world, so hard as to be impossible except to the Holy Spirit Himself, to drive a man away from the idea that he is to do something, or to be something, in order to his own salvation. Sinner, thou art the emptiness, and Christ the fullness; thou art the filthiness, and He the cleansing; thou art nothing, and He is all in all; and the sooner thou consentest to this the better. Have done with saying, “I would come to the Savior if this, and if that,” for this quibbling will delude, delay, and destroy thee. Come as thou art, just now, even at this moment, for Christ is not almost all, but all in all.

“True belief, and true repentance
Every grace that brings us nigh,
Without money
Come to Jesus Christ and buy.”

~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1006.cfm

Salvation belongeth unto the LORD: Thy blessing is upon Thy people. Selah. – Psalm 3:8

There are (those) in this world to whom Christ is something, but not much. They are anxious to save themselves, but since they must confess some imperfections they use the merits of Christ as a sort of makeweight for their slight deficiencies. Their robe is almost long enough, and by adding a little fringe of the Redeemer’s grace it becomes all they can wish. To say prayers, to go to church, to take the sacrament to observe Good Friday, these are the main reliances of many a religionist, and then if the coach sticks a little in a deeper rut than usual they call in the help of the Lord Jesus, and hope that He will put His shoulder to the wheel. They commonly say, “Well, we must do our best, then Christ will be our Savior, and God is very merciful.” They allow the blessed and all-sufficient work and sacrifice of the Savior to fill up their failures; and imagine that they are extremely humble in allowing so much as that. Jesus is to them a stopgap, and nothing more. I know not whether the condition of such people is one whit more desirable than that of those to whom Jesus is nothing at all, for this is a vile contempt and despising of Christ indeed, to think that He came to help you to save yourselves, to dream that He is a part Savior, and will divide the world and honor of salvation with the sinner. Those who yoke the sinner and the Savior together as each doing a part rob Christ of all His glory; and this is robbery indeed, to pilfer from the bleeding Lamb of God the due reward of His agonies. “He trod the winepress alone, and of the people there was none with Him.” In the work of salvation Jesus stands alone. Salvation is of the Lord. If Christ is not all to you He is nothing to you. He will never go into partnership as a part Savior of men. If He be something He must be everything, and if He be not everything He is nothing to you.~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1006.cfm

Christ is all in all. – Colossians 3:11.

The Apostle was arguing for holiness. He was earnestly contending against sin and for the maintenance of Christian graces, but he did not, as some do, who would like to be thought preachers of the gospel, resort to reasons inconsistent with the gospel of free grace. He did not bring forward a single legal argument; he did not say, “This do, and ye shall merit reward;” or, “This do not, and ye shall cease to be the beloved of the Lord.” He knew that he was writing to believers, who are not under the law but under grace, and he therefore used arguments fetched from grace, and suitable to the character and condition of “the elect of God, holy and beloved.”

In the new birth we are created in the image of Jesus, the second Adam, and in consequence all the distinctions that appertain to the old creation are rendered valueless; “there is neither Greek nor Jew, circumcision nor uncircumcision, Barbarian, Sythian, bond nor free: but Christ is all, and in all”: the argument from this fact being, that since the only abiding distinction in the new creation is Christ, we should take care that his image is most clearly stamped upon us so that we may not only confess with our tongues that we are Christians, but our conversation and our entire character shall bespeak us to be such. As you may recognize the Jew by his physiognomy, the Greek by his gracefulness, and the barbarian by his uncouthness; so should the Christian be known by his Christliness, by the light, love, and life of Christ streaming forth from him. This is the seal of God which is set upon the forehead of the faithful, and this is the mark of election which is in due season graven in the right hand of all the elect.~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1006.cfm