At the end of the game, it doesn’t matter who had more yards, who had more first-downs, or who had more sacks. All of those statistics are important, but ultimately, the only thing that matters is the ending score.
In the same way, there are many ways to measure the effectiveness of our belief systems, but if they do not lead people into the kingdom of God, we lose the game. The reason Christians need to share their faith in Christ is because salvation is not intuitive. People need to know that Jesus is the only way to enter the kingdom.