When we choose to make friends of people who are like minded, and share the same passion for the Lord and His ways, we will find our conversations and time together make us wiser and stronger in Him. Iron tools are made sharper, and fit for use, by rubbing them against other iron. One Bible commentary suggests the writer of this proverb purposefully mentions iron as the sharpener and not a whetstone, to emphasise that when one man has the same nature as another, not opposite, their mutual identity is what makes action possible and profitable. When we spend quality time with friends who love the Lord and are full of faith and live controlled by the Holy Spirit, our influence on each other quickens our ingenuity, enlivens our affections for the things of God, strengthens our judgment, excites us to virtuous and useful actions, and makes us, in all respects, better people. That's why we must choose our company wisely, so we can encourage one another and build each other up in the Word and in Faith. Some Christians use the argument that Jesus was a friend to sinners and spent time with unsavoury characters; to condone their poor choice of friends. But the Word shows us the moment Jesus met these people, they recognised His right Spirit, repented of their sins and dramatically changed their way of life, and most chose to follow after Him. He never chose to fit into their sinful environment to make them feel comfortable, rather, they encountered Him, were convicted of their sins and were immediately delivered out of that shameful life. 1 Corinthians 15:33 warns us to not be deceived, because evil company corrupts good habits. So choose your friends wisely, encourage each other in the things of God and together, actively see His kingdom priorities advanced.