kingdom program of the Messiah would be seen in a clearer fashion by the disciples (Acts 15:13-17).
This simply gives us a better understanding of John 2:11, when it states how the disciples "believed on Him." It was a developing, progressive and growing belief in the person and program of the Lord Jesus through the process of progressive revelation.
When a person believes in or on Christ today, they will exhibit faith in the person and work of Christ. Only this kind of faith is true saving faith (John 20:31, 1:12, 3:16, Acts 4:12). Anything short of a personal response to Christ is not genuine faith in Christ and does not result in salvation (see John 2:23-25, 8:31, 8:24).
The disciples had genuine faith from the start; however, they needed to allow that faith to grow and mature as their understanding of Christ's mission and person was explained to them. This was done throughout the earthly ministry of Christ and of course, further revealed to their lives after the Holy Spirit came to abide within them forever (John 16:14). It would be the Spirit of God who would reveal to their lives the person, work and loveliness of Jesus Christ in a more understandable and deeper way. Watchman Nee wrote, "God will answer all our questions in one way and one way only. Namely, by showing us more of his Son."