Divine grace is irresistible. God freely imputes our sin to Christ and his righteousness to sinners. Assurance is of the essence of saving faith. Christ's obedience and the divine promise is the ground of assurance. The practical syllogism may supplement the divine promises.
Evangelism is a Dominical mandate.
God reveals himself as desiring the redemption of all though he has decreed only the salvation of the elect. The free, universal, well-meant, offer of the gospel does not imply universal ability to believe. Not everyone will be saved. Only the elect will believe. None of the elect will be lost.