Biblical Reference:
The event where many disciples turn back is primarily recorded in the Gospel of John, specifically in John 6:60-66. This passage follows the discourse of Jesus as the Bread of Life, which presents a challenging teaching to His followers.

Context and Background:
The setting of this event is in Capernaum, following the miraculous feeding of the 5,000 and Jesus walking on water. The crowd, having witnessed these miracles, sought Jesus, hoping for more signs and physical sustenance. Jesus, however, redirects their focus from physical bread to spiritual nourishment, declaring Himself the Bread of Life.

Key Verses:
John 6:60-66 states:
"On hearing it, many of His disciples said, 'This is a difficult teaching. Who can accept it?' Aware that His disciples were grumbling about this, Jesus asked them, 'Does this offend you? Then what will happen if you see the Son of Man ascend to where He was before? The Spirit gives life; the flesh profits nothing. The words I have spoken to you are spirit and they are life. However, there are some of you who do not believe.' For Jesus had known from the beginning which of them did not believe and who would betray Him. Then Jesus said, 'This is why I told you that no one can come to Me unless the Father has granted it to him.' From that time on, many of His disciples turned back and no longer walked with Him."

Theological Significance:
This passage highlights several key theological themes:

1. The Challenge of Discipleship:
Jesus' teaching about eating His flesh and drinking His blood (John 6:53-58) was metaphorical, pointing to the necessity of fully partaking in His life and sacrifice. However, many found this teaching hard to accept, illustrating the cost and challenge of true discipleship.

2. Divine Revelation and Human Response:
Jesus emphasizes that understanding and accepting His teachings require divine revelation. He states, "No one can come to Me unless the Father has granted it to him" (John 6:65), underscoring the necessity of God's enabling grace for belief.

3. The Role of Faith:
The passage distinguishes between superficial followers and true disciples. While many were attracted to Jesus for His miracles, only those with genuine faith remained. This event serves as a reminder that faith is not merely intellectual assent but a deep, personal commitment to Christ.

4. The Sovereignty of God:
Jesus' awareness of those who did not believe and who would betray Him (John 6:64) points to His divine omniscience and the sovereignty of God in the unfolding of redemptive history.

Implications for Believers:
The turning back of many disciples challenges believers to examine the depth and authenticity of their faith. It calls for a commitment that goes beyond seeking personal benefit to embracing the full message of the Gospel, even when it is difficult to understand or accept. This passage encourages believers to rely on the Holy Spirit for understanding and to remain steadfast in their walk with Christ, trusting in God's sovereign plan.