Another way to Know Jesus Is God's Son is by the persecution the Apostles were willing to put up with to share the truth about Jesus' death on the cross and resurrection from the dead. They did all of this, because it was the truth, so that all can have eternal life who believe Jesus Is God's Son, and Our Savior. If they had part of some conspiracy, they wouldn't have been willing to withstand humiliation, ridicule, beatings, imprisonment, and sometimes death to keep it going. Their willingness to suffer to share this truth proves that Jesus Christ Is truly the Son of God!
Remember that Jesus Christ of the seed of David was raised from the dead according to my gospel: Wherein I suffer trouble, as an evil doer, even unto bounds; but the Word of God is not bound. Therefore I endure all things for the elect's [sake], that they may also obtain the salvation which is in Christ Jesus with eternal glory. It is a faithful saying: For if we be dead with Him, we shall also live with Him: 2 Timothy 2:8-11