Actually, the first believers / disciples were recognized by their calling on the name of the Lord Jesus – that’s how Paul, when he was Saul, would find them and then imprison them. This practice of calling on the name of the Lord is not something new or invented by someone, but it is a life practice that has been lost(like many other truths and healthy practices) during the centuries. Paul begins his first epistle to the Corinthians “To the church of God which is in Corinth, to those who have been sanctified in Christ Jesus, the called saints, with all those who call upon the name of our Lord Jesus Christ in every place, who is theirs and ours” (1 Cor. 1:2). Here’s a note I enjoyed on the verse in Acts 2:21(which quotes from the Old Testament) “and it shall be that everyone who calls on the name of the Lord shall be saved” via the Recovery Version:
Calling on the name of the Lord is not a new practice that began with the New Testament. Rather, it began with Enosh, the third generation of mankind, in Gen. 4:26. It was continued by Job (Job 12:4; 27:10), Abraham (Gen. 12:8; 13:4; 21:33), Isaac (Gen. 26:25), Moses and the children of Israel (Deut. 4:7), Samson (Judg. 15:18; 16:28), Samuel (1 Sam. 12:18; Psa. 99:6), David (2 Sam. 22:4, 7; 1 Chron. 16:8; 21:26; Psa. 14:4; 17:6; 18:3, 6; 31:17; 55:16; 86:5, 7; 105:1; 116:4, 13, 17; 118:5; 145:18), the psalmist Asaph (Psa. 80:18), the psalmist Heman (Psa. 88:9), Elijah (1 Kings 18:24), Isaiah (Isa. 12:4), Jeremiah (Lam. 3:55, 57), and others (Psa. 99:6), all of whom practiced this in the Old Testament age. Isaiah charged the seekers of God to call upon Him (Isa. 55:6). Even the Gentiles knew that the prophets of Israel had the habit of calling on the name of God (Jonah 1:6; 2 Kings 5:11). The Gentile raised up by God from the north also called upon His name (Isa. 41:25). It is God’s commandment (Psa. 50:15; Jer. 29:12) and desire (Psa. 91:15; Zeph. 3:9; Zech. 13:9) that His people call on Him. This is the joyful way to drink from the fountain of God’s salvation (Isa. 12:3-4) and the enjoyable way to delight oneself in God (Job 27:10), that is, to enjoy Him. Hence, God’s people must call upon Him daily (Psa. 88:9). Such a jubilant practice was prophesied by Joel (Joel 2:32) concerning the New Testament jubilee.
In the New Testament, calling on the name of the Lord was first mentioned by Peter, here, on the day of Pentecost, as the fulfillment of Joel’s prophecy. This fulfillment is related to God’s outpouring of the all-inclusive Spirit economically upon His chosen people that they may participate in His New Testament jubilee. Joel’s prophecy and its fulfillment concerning God’s New Testament jubilee have two aspects: on God’s side, He poured out His Spirit in the ascension of the resurrected Christ; on our side, we call on the name of the ascended Lord, who has accomplished all, attained unto all, and obtained all. Calling on the Lord’s name is vitally necessary in order for us, the believers in Christ, to participate in and enjoy the all-inclusive Christ with all He has accomplished, attained, and obtained (1 Cor. 1:2). It is a major practice in God’s New Testament economy that enables us to enjoy the processed Triune God for our full salvation (Rom. 10:10-13). The early believers practiced this everywhere (1 Cor. 1:2), and to the unbelievers, especially the persecutors, it became a popular sign of Christ’s believers (9:14, 21). When Stephen suffered persecution, he practiced this (7:59), and his practice surely impressed Saul, one of his persecutors (7:58-60; 22:20). Later, the unbelieving Saul persecuted the callers (9:14, 21) by taking their calling as a sign. Immediately after Saul was caught by the Lord, Ananias, who brought Saul into the fellowship of the Body of Christ, charged him to be baptized, calling on the name of the Lord, to show others that he too had become such a caller. By his word to Timothy in 2 Tim. 2:22, Paul indicated that in the early days all the Lord’s seekers practiced such calling. Undoubtedly, he was one who practiced this, since he charged his young co-worker Timothy to do this that Timothy might enjoy the Lord as he did.
The Greek word for call on is composed of on and call (by name); thus, it is to call out audibly, even loudly, as Stephen did (7:59-60).
Lord, make us the ones who have such a deep intimate relationship with You, those who call on Your name in every place!