Definition and Significance:
Calling on the Name of the LORD is a biblical expression that signifies invoking, worshiping, and seeking the presence and assistance of God. This practice is deeply rooted in the Judeo-Christian tradition and is seen as an act of faith, dependence, and reverence towards God. It is both a personal and communal act of devotion, often associated with prayer, worship, and the acknowledgment of God's sovereignty and power.

Biblical Instances:

1. Genesis 4:26 · The practice of calling on the Name of the LORD is first mentioned in the early chapters of Genesis: "And to Seth also a son was born, and he called him Enosh. At that time men began to call on the name of the LORD." This indicates the beginning of a formalized worship and recognition of God among humanity.

2. Genesis 12:8 · Abraham, the patriarch of the faith, is noted for building altars and calling on the Name of the LORD: "From there Abram moved on to the hill country east of Bethel and pitched his tent, with Bethel on the west and Ai on the east. There he built an altar to the LORD and called on the name of the LORD." This act signifies Abraham's devotion and reliance on God as he journeyed in faith.

3. 1 Kings 18:24 · The prophet Elijah challenges the prophets of Baal to a contest on Mount Carmel, emphasizing the power of calling on the true God: "Then you call on the name of your god, and I will call on the name of the LORD. The God who answers by fire, He is God." This event underscores the belief in God's responsiveness to those who call upon Him in truth.

4. Psalm 116:4 · The psalmist expresses a personal plea for deliverance: "Then I called on the name of the LORD: 'O LORD, deliver my soul!'" This highlights the personal nature of calling on God in times of distress and need.

5. Joel 2:32 · The prophet Joel speaks of a future time of salvation: "And everyone who calls on the name of the LORD will be saved; for on Mount Zion and in Jerusalem there will be deliverance, as the LORD has promised, among the remnant called by the LORD." This prophecy is later echoed in the New Testament, emphasizing the universality of God's offer of salvation.

6. Acts 2:21 · On the day of Pentecost, Peter quotes Joel's prophecy, affirming its fulfillment through Jesus Christ: "And everyone who calls on the name of the Lord will be saved." This marks the expansion of God's promise of salvation to all who believe in Jesus.

7. Romans 10:13 · The Apostle Paul reiterates the promise of salvation for those who call on the Lord: "for, 'Everyone who calls on the name of the Lord will be saved.'" This verse underscores the accessibility of salvation through faith in Christ.

Theological Implications:
Calling on the Name of the LORD is an acknowledgment of God's authority, presence, and willingness to engage with His creation. It reflects a heart posture of humility, trust, and reliance on God's character and promises. In the New Testament, this practice is closely associated with the person and work of Jesus Christ, through whom believers have direct access to God.

Practical Application:
For believers, calling on the Name of the LORD is an integral part of their spiritual life. It involves prayer, worship, and the invocation of God's help in daily living. It is a reminder of the believer's relationship with God and the assurance of His presence and power in their lives.