1 Timothy 1:16

might Jesus Christ show forth all his longsuffering, for an ensample of them that should thereafter believe on him unto eternal life.

Paul's argument here is that by pardoning the chief of the band of brigands, Jesus Christ had, by implication, extended an invitation to receive forgiveness to all the lesser sinners who made up the company!

For an ensample ... That the blessed apostle does not here overestimate the significance of his conversion is discernible throughout history. Paul's conversion, along with the resurrection of Christ, is part of the incontrovertible evidence of the integrity and authenticity of the Christian faith.

Believe on him unto eternal life ... This strongly suggests Romans 10:10,11; and significantly "believing on" Christ in both passages is "unto" eternal life, and salvation, as is ever the case in the New Testament. The sacred writers were diligent never to leave an impression that merely "believing on" the Lord Jesus Christ surely led to eternal life, but merely in the direction of it, "unto life." The apostle John gave the classical example of a case in which it did not bestow eternal life (John 12:42,43); but in even that instance "believing on" the Lord led in the direction of it.

Eternal life ... Christianity is involved with the supernatural, a fact abundantly clear in such an expression as this. The grand scope and purpose of Christianity is to accomplish the forgiveness of people's sins (salvation), and in the upper and better world usher them into eternal and better life where they may have in utmost joy and tranquillity, fellowship with the Creator forever.