The phrase "the letter and the spirit" is derived from the Apostle Paul's writings, particularly in his second epistle to the Corinthians. This concept is central to understanding the distinction between the Old Covenant, characterized by the Mosaic Law, and the New Covenant, which is marked by the indwelling of the Holy Spirit and the grace of God through Jesus Christ.

Biblical References:

1. 2 Corinthians 3:6 : "He has qualified us as ministers of a new covenant, not of the letter but of the Spirit; for the letter kills, but the Spirit gives life." This verse highlights the transformative power of the Holy Spirit in contrast to the written code of the Law. Paul emphasizes that the Law, while holy and righteous, ultimately brings death because it exposes sin without providing the means for overcoming it. In contrast, the Spirit imparts life, enabling believers to fulfill the righteous requirements of the Law through the power of Christ.

2. Romans 7:6 : "But now, having died to what bound us, we have been released from the law, so that we serve in the new way of the Spirit, and not in the old way of the written code." Here, Paul explains that believers are no longer bound by the Law's demands because they have been released through Christ's death and resurrection. The "new way of the Spirit" refers to living under the guidance and empowerment of the Holy Spirit, which leads to true righteousness and holiness.

3. Romans 2:29 : "But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the written code. Such a man’s praise does not come from men, but from God." This passage underscores the internal transformation that the Spirit brings, contrasting it with mere external adherence to the Law. True circumcision, or covenant relationship with God, is a spiritual matter, accomplished by the Spirit's work in the heart.

Theological Implications:

The distinction between the letter and the spirit is foundational for understanding the transition from the Old Covenant to the New Covenant. The "letter" refers to the literal, written commandments of the Mosaic Law, which, while good, were insufficient for salvation because they could not change the human heart. The Law served to reveal sin and point to the need for a Savior (Galatians 3:24).

The "spirit," on the other hand, represents the life-giving power of the Holy Spirit, who enables believers to live in accordance with God's will. This is not a rejection of the Law's moral standards but a fulfillment of them through the Spirit's work. The Spirit writes God's laws on believers' hearts (Jeremiah 31:33; Hebrews 8:10), empowering them to live out the righteousness that the Law demands.

Practical Application:

For Christians, the concept of the letter and the spirit calls for a life led by the Holy Spirit rather than mere legalistic adherence to rules. It encourages believers to seek a deeper relationship with God, characterized by love, grace, and obedience that flows from a transformed heart. This transformation is evidenced by the fruit of the Spirit (Galatians 5:22-23) and a life that reflects the character of Christ.

In summary, the letter and the spirit represent two approaches to God's commandments: one that is external and powerless to save, and another that is internal and life-giving, made possible through the work of the Holy Spirit in the believer's life.