It is a challenge to determine who the first Christian might be.
One might say the first Christians were those who first followed Jesus. John 1:36-51 lists a number of men who later became apostles: Andrew, Simon Peter, Philip, and Nathanael. But there were different phases of commitment, culminating in the pouring out of the holy spirit in Acts 2:1-4: On the Day of Pentecost, the holy spirit came on those gathered together, and they began to speak with other tongues (languages) by the power of the spirit.
But the name “Christian” was not adopted until after the conversion of Saul to the Apostle Paul, when Paul was brought to Antioch by Barnabas. Acts 11:26: Paul and Barnabas met with the church in Antioch for a year, and it was in Antioch that the disciples were first called Christians.
Who started the Christian movement originally? There are various phases in answer to this question.
*Our Heavenly Father foreknew and set the standards for Christians as a spiritual family. Ephesians 1:3-6: Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ, just as He chose us in him before the foundation of the world, that we should be holy and blameless before Him. In love He predestined us to adoption as sons through Jesus Christ to Himself, according to the kind intention of His will to the praise of the glory of His grace, which He freely bestowed on us in the Beloved.
*John the Baptist prepared the way for the ministry of Jesus, proclaiming Behold the Lamb of God, and leading those with interest to Jesus (John 1:29-36, for example). Mark 1:1-4: The beginning of the gospel of Jesus Christ, the son of God. As it is written in Isaiah the prophet, “Behold, I send my messenger before your face, who will prepare your way; the voice of one crying in the wilderness, ‘Make ready the way of the Lord, make his paths straight.’” John the Baptist appeared in the wilderness preaching a baptism of repentance for the forgiveness of sins.
*Jesus was the head of the Christian movement of believers, the author and finisher of our faith. Hebrews 12:2
*The faith of the original followers of Christ who were the first to receive the holy spirit, and especially the Apostle Peter, had a major effect on the original spread of the gospel. Acts 2:1-4 On the Day of Pentecost, the holy spirit came on those gathered together, and they began to speak with other tongues (languages) by the power of the spirit.?
Devout Jews living in Jerusalem heard the voices of these followers of Jesus in their own language/dialect as they proclaimed the mighty deeds of God. Acts 1:5-11
Peter testified to these Jews, and invited them to be baptized in the name of Jesus Christ, and to receive the gift of the Holy spirit. Acts 2:14-40
Then in Acts 2:41 it states: those who had received his word were baptized; and there were added that day about three thousand souls.
*The sharing of the gospel continued with a great impact by the Apostle Paul. During his ministry, Paul traveled more than 10,000 miles and established at least 14 churches, with journeys to various places including Greece, Turkey and Syria. (Acts 13-14, 16:23-20:38) And as mentioned above, the followers of Christ were first called “Christians” after Barnabas and Paul were in Antioch.
Thus the Christian spiritual family became well established and continued to grow throughout the world.
It is important to note that the true Christian movement was appointed by God and Christ to remain simple, with humble leadership, not misusing power or making money, but focused on the wellbeing of the flock.
1 Peter 5:1-3: Therefore, I exhort the elders among you, as your fellow elder and witness of the sufferings of Christ, and a partaker also of the glory that is to be revealed, shepherd the flock of God among you, exercising oversight not under compulsion, but voluntarily, according to the will of God; and not for sordid gain, but with eagerness; nor yet as lording it over those allotted to your charge, but proving to be examples to the flock.