Definition and Significance:
The term "register" in a biblical context refers to a written record or list, often used to document genealogies, censuses, or important events. Registers were crucial in maintaining the lineage and heritage of the Israelite tribes, ensuring the continuity of priestly and royal lines, and preserving the history of God's people.

Biblical References:

1. Genealogical Registers:
Genealogical registers are prominent in the Bible, particularly in the Old Testament. These records were essential for establishing tribal identities and inheritance rights. In the Book of Numbers, God commands Moses to take a census of the entire Israelite community by their clans and families, listing every male by name, one by one (Numbers 1:2). This register was vital for organizing the tribes during their wilderness journey and for allotting land in the Promised Land.

2. Priestly Registers:
The priestly registers were critical for determining the legitimacy of those serving in the temple. In the Book of Ezra, after the Babylonian exile, a register was used to verify the lineage of the priests. Those who could not find their family records were excluded from the priesthood until a priest could consult the Urim and Thummim (Ezra 2:62-63). This ensured the purity and sanctity of the priestly office.

3. Royal Registers:
The royal registers documented the lineage of kings, particularly in the books of Chronicles. These records affirmed the Davidic line, which was central to the messianic prophecies. The Chronicler meticulously records the genealogy from Adam to the post-exilic community, emphasizing the continuity of God's covenant with David (1 Chronicles 1-9).

4. Civic Registers:
Civic registers were used to organize the community and ensure proper governance. Nehemiah, upon returning to Jerusalem, found a register of those who had first returned from exile. This list was crucial for rebuilding the city and reestablishing the community according to God's law (Nehemiah 7:5).

Theological Implications:
Registers in the Bible underscore the importance of identity, heritage, and divine order. They reflect God's sovereignty in history, His faithfulness to His promises, and the meticulous care with which He preserves His people. The genealogies leading to Jesus Christ, as recorded in the Gospels of Matthew and Luke, highlight the fulfillment of God's redemptive plan through the lineage of David, affirming Jesus as the promised Messiah (Matthew 1:1-17, Luke 3:23-38).

Cultural and Historical Context:
In ancient Near Eastern cultures, registers were not unique to Israel. Other civilizations also maintained records for administrative and religious purposes. However, the biblical registers are distinct in their theological significance, serving as a testament to God's covenantal relationship with His people. They provided a framework for understanding Israel's identity and mission in the world.

Conclusion:
The concept of the register in the Bible is multifaceted, encompassing genealogical, priestly, royal, and civic dimensions. These records were vital for maintaining the integrity and continuity of the Israelite community, reflecting God's providential care and the unfolding of His divine plan throughout history.