Definition and Significance
Baptism into Christ is a fundamental Christian sacrament and rite of initiation that symbolizes the believer's identification with the death, burial, and resurrection of Jesus Christ. It represents a public declaration of faith and a commitment to follow Christ, signifying the washing away of sins and the believer's entry into the Christian community. This act is seen as an outward expression of an inward transformation, marking the believer's new life in Christ.

Biblical Foundation
The New Testament provides several key passages that outline the theological significance and practice of baptism. In the Great Commission, Jesus commands His disciples, "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit" (Matthew 28:19). This directive establishes baptism as an essential component of discipleship and evangelism.

The Apostle Paul further elucidates the spiritual implications of baptism in his epistles. In Romans 6:3-4, he writes, "Or aren’t you aware that all of us who were baptized into Christ Jesus were baptized into His death? We were therefore buried with Him through baptism into death, in order that, just as Christ was raised from the dead through the glory of the Father, we too may walk in newness of life" . Here, baptism is portrayed as a participation in the death and resurrection of Christ, symbolizing the believer's death to sin and rebirth into a life of righteousness.

Theological Implications
Baptism into Christ is not merely a ritualistic act but a profound spiritual experience that signifies the believer's union with Christ. In Galatians 3:27, Paul states, "For all of you who were baptized into Christ have clothed yourselves with Christ" . This imagery of being clothed with Christ suggests a transformation of identity, where the believer takes on the character and righteousness of Jesus.

Furthermore, baptism is associated with the forgiveness of sins and the gift of the Holy Spirit. In Acts 2:38, Peter exhorts the crowd, "Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit" . This passage highlights the integral role of baptism in the process of salvation and the believer's empowerment by the Holy Spirit.

Mode and Practice
The mode of baptism has been a subject of theological discussion, with practices varying among Christian denominations. The New Testament suggests immersion as the primary mode, as seen in the baptism of Jesus by John the Baptist, where "Jesus came up out of the water" (Mark 1:10). Immersion symbolizes the believer's full identification with the death, burial, and resurrection of Christ.

However, other modes such as pouring or sprinkling are also practiced, particularly in traditions that emphasize the covenantal aspect of baptism, akin to circumcision in the Old Testament. Regardless of the mode, the essential element of baptism is the believer's faith and repentance, as well as the invocation of the Triune God.

Conclusion
Baptism into Christ remains a central and unifying practice within Christianity, embodying the core tenets of the faith. It serves as a powerful testament to the transformative work of Christ in the life of the believer, marking the beginning of a lifelong journey of discipleship and spiritual growth.