...and we develop inner strength and power to endure anything that comes our way. A sword weilded and tried with fire becomes sharp and formidable.
We are like the sword coming from a lowly raw iron and purified in fire and designed by the Hand of God Himself.
Trials and sufferings help us develop a strong relationship with God and our utmost dependent on Him are what make us become mature in character. It is then that eternal salvation is achieved not because we deserve it but because we have chosen to be molded in God's hands.
"Moreover [let us also be full of joy now!] let us exult and triumph in our troubles and rejoice in our sufferings, knowing that pressure and affliction and hardship produce patient and unswerving endurance. And endurance (fortitude) develops maturity of character (approved faith and tried integrity). And character [of this sort] produces [the habit of] joyful and confident hope of eternal salvation."
Romans 5:3-4 AMPC