Chapter 18.3

iii.This infallible assurance doth not so belong to the essence of faith but that a true believer may wait long and conflict with many difficulties before he be partaker of it: yet, being enabled by the Spirit to know the things which are freely given him of God, he may, without extraordinary revelation, in the right use of ordinary means, attain thereunto. And therefore it is the duty of everyone to give all diligence to make his calling and election sure; that thereby his heart may be enlarged in peace and joy in the Holy Ghost, in love and thankfulness to God, and in strength and cheerfulness in the duties of obedience, the proper fruits of this assurance: so far is it from inclining men to looseness. 

The opening line of this section refers to an ongoing debate within post-Reformation Christianity. Is assurance of the very essence of faith? In other words, does faith always come with some measure of assurance? Or is it possible at times for a genuine believer to lack any certainty that he or she is saved?

The Confession answers this difficult question with typical balance. Ultimately, faith has at least some assurance of salvation, but this may not come right away. This in itself is reassuring, because it delivers a doubting believer from despair. It is normal for Christians to go through seasons of spiritual discouragement that include serious doubts about their salvation.

What should Christians do when they experience such doubts? When we have our spiritual struggles, it is tempting to neglect our relationship with God. But the wise pastors who wrote the Confession of Faith tell us to do exactly the opposite. God has promised to meet us is in the "ordinary means" of prayer, the sacraments, and the Word of God. So we should continue to read our Bibles, talk with God through prayer, and participate in the worship of the local church--even when we don't particularly feel like doing any of these things. 

This is not simply good advice; it is the believer's duty. The Scripture says, "Be all the more diligent to make your calling and election sure" (2 Peter 1:10). If we do this, then in his own good time and by the work of the Holy Spirit, God will restore us to peace, joy, love, and all the other good fruit that come with the assurance of faith.  
Dr. Philip Ryken is the president of Wheaton College and the author of numerous books, the most recent of which is Loving the Way Jesus Loves (Crossway, 2012).