The crowd that was with Jesus when He raised Lazarus from the dead is described in (11:45; 12:1,9-11).

John 11:45  Therefore many of the Jews who had come to visit Mary, and had seen what Jesus did, put their faith in him.

John 12:1  Six days before the Passover, Jesus arrived at Bethany, where Lazarus lived, whom Jesus had raised from the dead.

John 12:9-11  Meanwhile a large crowd of Jews found out that Jesus was there and came, not only because of him but also to see Lazarus, whom he had raised from the dead.  So the chief priests made plans to kill Lazarus as well,  for on account of him many of the Jews were going over to Jesus and putting their faith in him.

Notice that not only the raising of Lazarus, which was the more important of the two, but also the manner of his raising are here mentioned, since the latter had evidently made a very large impression upon those present.

The crowd is bearing witness to Jesus. Note that in this gospel there are 7 who bear witness to Jesus: Each of the persons of the trinity, the Father (5:31-32, 34, 37, 8:18), Christ Himself (8:14, 18, 3:11, 32), and the Spirit (15:26, 16:14). Also the works of Christ (5:36, 10:25, 14:11, 15:24), the scriptures (5:39, 5:45-47), John the Baptist (1:7), and various human witnesses (15:27, 19:35, 21:24, 4:39, 12:17).

Witnesses to Jesus

The Father:

John 5:31-32  “If I testify about myself, my testimony is not valid.  There is another who testifies in my favour, and I know that his testimony about me is valid.

John 5:34  Not that I accept human testimony; but I mention it that you may be saved.

John 5:37  And the Father who sent me has himself testified concerning me. You have never heard his voice nor seen his form,

John 8:18  I am one who testifies for myself; my other witness is the Father, who sent me.”

Christ Himself:

John 8:14  Jesus answered, “Even if I testify on my own behalf, my testimony is valid, for I know where I came from and where I am going. But you have no idea where I come from or where I am going.

John 8:18  I am one who testifies for myself; my other witness is the Father, who sent me.”

John 3:11  I tell you the truth, we speak of what we know, and we testify to what we have seen, but still you people do not accept our testimony.

John 3:32  He testifies to what he has seen and heard, but no-one accepts his testimony.

The Spirit:

John 15:26  “When the Counsellor comes, whom I will send to you from the Father, the Spirit of truth who goes out from the Father, he will testify about me.

John 16:14  He will bring glory to me by taking from what is mine and making it known to you.

The works of Christ:

John 5:36  “I have testimony weightier than that of John. For the very work that the Father has given me to finish, and which I am doing, testifies that the Father has sent me.

John 10:25  Jesus answered, “I did tell you, but you do not believe. The miracles I do in my Father’s name speak for me,

John 14:11  Believe me when I say that I am in the Father and the Father is in me; or at least believe on the evidence of the miracles themselves.

John 15:24  If I had not done among them what no-one else did, they would not be guilty of sin. But now they have seen these miracles, and yet they have hated both me and my Father.

The scriptures:

John 5:39  You diligently study the Scriptures because you think that by them you possess eternal life. These are the Scriptures that testify about me,

John 5:45-47  “But do not think I will accuse you before the Father. Your accuser is Moses, on whom your hopes are set.  If you believed Moses, you would believe me, for he wrote about me.  But since you do not believe what he wrote, how are you going to believe what I say?”

John the Baptist:

John 1:7  He came as a witness to testify concerning that light, so that through him all men might believe.

Other people:

John 15:27  And you also must testify, for you have been with me from the beginning.

John 19:35  The man who saw it has given testimony, and his testimony is true. He knows that he tells the truth, and he testifies so that you also may believe.

John 21:24  This is the disciple who testifies to these things and who wrote them down. We know that his testimony is true.

John 4:39  Many of the Samaritans from that town believed in him because of the woman’s testimony, “He told me everything I ever did.”

John 12:17  Now the crowd that was with him when he called Lazarus from the tomb and raised him from the dead continued to spread the word.

Those who have seen the things Jesus has done are moved to tell others about it. So it is today.