John 20:9

John’s faith rested on the evidence that he had seen. [Note: See Zane C. Hodges, "Form-Criticism and the Resurrection Accounts," Bibliotheca Sacra 124:496 (October-December 1967):339-48.] Later he and the other disciples would have additional reasons for believing that Jesus had risen, namely, the prophetic Scriptures that the Resurrection fulfilled (e.g., Leviticus 23:11; Psalms 16:10-11; Psalms 110:1; Psalms 110:4; Isaiah 53:11-12; Hosea 6:2; cf. Acts 2:24-31; 1 Corinthians 15:3-7). John’s faith took a step forward here, but it was not yet as strong as it would be (cf. Luke 24:25-27; Luke 24:32; Luke 24:44-47).

"The empty cross and the empty tomb are God’s ’receipts’ telling us that the debt has been paid." [Note: Wiersbe, 1:387.]