18.3 The infallible assurance of salvation is not an essential part of salvation, for a true believer may wait for a long time, and struggle with many difficulties, before he attains to it. It is not a matter of extraordinary revelation, for if he makes a right use of the means of grace, and is enabled by the Spirit to know the things that believers receive freely from God, he may well attain to it. It therefore becomes the duty of every one to be as diligent as possible in making his calling and election sure. By doing this he will experience greater peace and joy in the Holy Spirit, greater love and thankfulness to God, and an increased strength and cheerfulness in dutiful obedience. These things are the natural outcome of the assurance of salvation, and they constitute strong evidence that assurance does not lead men into loose living. Ps. 77:1-12; Ps. 88; 119:32; Isa. 50:10; Rom. 5:1,2,5; 6:1,2; 14:17; Titus 2:11,12,14; Heb. 6:11,12; 1 John 4:13.
18.4 True believers may find that their assurance of salvation fluctuates; sometimes more, sometimes less. They may prove neglectful in preserving it, as for example, if they give way to some particular sin that wounds their conscience and grieves the Spirit; or a strong temptation may suddenly spring upon them; or God may see fit to withdraw 'the light of His countenance' and cause darkness to envelop them, a course He sometimes takes even with those who fear His name. Yet, whatever happens, certain things inevitably remain with them-the new nature which is born of God, the life of faith, the love of Christ and the brethren, sincerity of heart and conscience of duty-and by reason of these and through the work carried on by the Spirit within them, the assurance of salvation may in due time be revived. In the meantime the same influences preserve them from utter despair. Ps. 30:7; 31:22; 42:5,11; 51:8,12,14; 77:7,8; 116:11; Song 5:2,3,6; Lam. 3:26-31; Luke 22:32; 1 John 3:9.