Faith is a gift of God. It is like a seed planted in our heart. The smallest seed of faith can move mountains. The Bible says that we live by faith. We are saved by faith. We overcome obstacles in life by faith.
When we water the seed of faith, our faith will grow stronger and increase. The apostle Peter is saying that we should devote ourselves to develop our faith or to supplement it. As a seed faith is full of potensial for dynamic growth and development. Peter speaks of an unfolding of faith (2 Pet 1:7-11)
Out of the seed of faith planted in our heart by God will emerge goodness, and out of goodness will emerge understanding of God, and out understanding and knowing God will emerge inner strength and self-control, and out of this inner strength will emerge patient endurance, and out of patient endurance will emerge godliness, and out of godliness will emerge mercy towards our brothers and sisters, and out of mercy will emerge unending love.
All these virtues are inherent in the seed of faith that God is planting in our heart. They have been planted deep within us by the Spirit of God. Actually we possess them in abundant supply by the grace of God. This unfolding of faith will keep us from being inactive or fruitless in our pursuit of knowing Jesus Christ more intimately. If these virtues are absent in our lives we will be blind, constantly closing our eyes to the mystery of faith, forgetting our innocence - for our sins have been washed away.
Therefore it is very important that we are eager to confirm and validate that God has invited us to salvation and claimed us his very own. When we do these things, we will never stumble. As a result God will give us a triumphant entrance into the eternal kingdom of our Lord Jesus Christ.
It is also possible to see this as a spiritual mathematical equation. Faith pluss goodness equals understanding and knowledge of God. Goodness pluss understanding equals inner strength and self-control. Understanding pluss self-control equals patience. Inner strength pluss patience equals godliness. Patience pluss godliness equals mercy. Godliness pluss mercy equals unending love. These qualities are meant to be limitless as our faith keeps unfolding.