Faith in the person of Christ, not merely in the fact that Jesus is the Son of God.
God
Also personal. To believe God, is to believe the message which comes from Him. See on Joh 1:12.
Hath made - hath believed (πρποίηκεν - πεπίστευκεν)
The perfect tense marks the two results expressed by the verbs as connected with a past act. The act perpetuates itself in the present condition of the unbeliever.
Believed on the witness (πεπίστευκεν εἰς τὴν μαρτυρίαν)
The phrase occurs only here. See on Joh 1:12. In one other case to believe on is used with an object not directly personal, πιστεύετε εἰς τὸ φῶς; but the reference is clearly to the personal Christ as the Light of the World (Joh 8:12).