For all of you who were baptized into Christ have clothed yourselves with Christ.Galatians 3:27(NASB)
When we were saved by grace through faith in the death, burial, and Resurrection of the Lord Jesus Christ, we were positioned in Him and identified with Him. We were clothed with Christ, placed into the Body of Christ, and made One with Him... and Paul calls this being 'baptised into Christ'. By faith, we became One with Christ and identified with Him, such that His righteousness became our righteousness, His resurrected life became our eternal life, His heavenly inheritance became our glorious inheritance, which will never fade away, but is kept for us in heaven.
Before salvation, we were covered in sin, immersed in sin, and identified with sin. We were conceived in sin by sinful parents, born into a sinful world, and had an imputed sinful nature. As sinners, we had a relationship with sin, we were immersed in sin, we were 'baptised' into sin. Before we were saved, we were estranged from God BUT when we were saved by grace through faith in Christ, our sin was forgiven and we came into a living union with Him - a spiritual union which joins all believers to Christ our Saviour Who is the Head of the Body. And it was the Holy Spirit, Himself, that placed us into union with the Lord Jesus Christ. He baptised us INTO Christ the moment we first believed.
At salvation, we put off the old and put on the new. We were taken out of our old relationship with sin and united together in a new relationship with Christ. As believers, we are clothed with Christ, made One with Him, and united together as members of His spiritual Body, which is the Church - and Paul calls this being 'baptised into Christ'.
Union with Christ is the most wonderful truth of our salvation that staggers the imagination... for the Holy Spirit baptises us into the Lord Jesus and then comes to live inside our bodies. This spiritual baptism only happens once... at the point of salvation, but from that moment on, through time and into eternity, believers will never be out of union with Christ. This position of security does not depend on our merit or demerit. It does not depend on what we do or what we don't do, but on the efficacy of the finished work of Christ at Calvary.
Our position in Christ has nothing to do with us but is simply a free gift of God's grace, by faith in Christ, and remains eternally unchanging and eternally secure. Oh, we may lose fellowship with the Lord when we sin, and we will remain out of fellowship with Him until we confess our wrongdoing - but our position in Christ is unchangeable and unchanging. Our union with Christ which begins the moment that we were born again can never be lost - and Paul calls this being 'baptised into Christ'.
Although our baptism into Christ (our union with Him) takes place at one specific point in time, we are commanded to be filled with the Spirit, day by day, and to walk in spirit and truth throughout our Christian life so that we may enjoy holy communion with our Heavenly Father and remain in sweet fellowship with Him as we obey His Word and follow His leading.
Heavenly Father, thank You that all believers have been united together with Christ and identified with Him through the baptism of the Holy Spirit, the moment we first believed. Thank You that He is our Comforter and Councillor Who has bestowed on us eternal blessings of grace. Thank You that as members of Christ’s Body, we have the peace of God in our hearts, the life of Christ in our souls, and the fellowship of the Holy Spirit to guide us into all truth. In Jesus' name, AMEN.