We can have confidence that we have eternal life based on what the Word of God Says. If our confidence is based on anything other than God’s holy word than we are on a foundation that is built on quicksand. That is why the scripture says: (Romans- 3:) 21 But now apart from the law the righteousness of God has been made known, to which the Law and the Prophets testify. 22 This righteousness is given through faith in Jesus Christ to all who believe. There is no difference between Jew and Gentile, 23 for all have sinned and fall short of the glory of God, 24 and all are justified freely by his grace through the redemption that came by Christ Jesus. It also says: Romans- 5:8
But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.