By “Let the Word of God loose until the God of the Word causes the person to be born again.” That is perhaps the shortest, and practically most meaningful answer to the burden of our souls for the salvation of our unsaved family, friends, and neighbours.
In John 3 Jesus explains how people get saved when speaking to Nicodemus and affirms that the actual moment of salvation is like the wind, not visible in any way, but producing results that prove that indeed the person has been born again. Ephesians 2 describes sinners before being saved as spiritually dead until God makes them spiritually alive. In other words, we cannot cause someone to be born again, it is God’s work, and we cannot even coerce it through certain prayers, confessions, or traditions.
God does the work of the new birth. What then can we do as concerned family, friends, and neighbours? We can bring them face-to-face with God and with their own conditions through the Word of God. Hebrews 4:12-13 affirm that the Word is God’s way of making us come to grips with our accountability before God. It is through the Scriptures that each is led to salvation (2 Tim 3:15).
So when you desire so strongly for the salvation of a family member, friend, neighbour, or even a stranger, open your Bible, read and explain a passage, and then tell them, with that knowledge, to go and sort it out further with the Lord. And do that over and over and over again until the Lord makes their souls alive, and the fruit of that is seen in their repentance and faith.