“Secondly, it is the very nature of spiritual life to grow. Wherever they principle of this life is to be found, it can be no different for it must grow. "But the path of the just is as the shining light, that shineth more and more unto the perfect day" (Prov. 4:18); "The righteous also shall hold on his way, and he that hath clean hands shall be stronger and stronger" (Job 17:9). This refers to the children of GOd, who are compared to palm and cedar trees (Psa. 92:12). As natural as it is for children and trees to grow, so natural is growth for the regenerated children of God.
Thirdly, the growth of His children is the goal and objective God has in view by administering the means of grace to them. "And He gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; for the perfecting of the saints...that we henceforth be no more children...but speaking the truth in love, may grow up into Him in all things, which is the Head" (Eph. 4:11-15). This is also to be observed in 1 Peter 2:2: "as newborn babes, desire the sincere milk of the word, that ye may grow thereby, " God will reach His goal and His word will not return to Him void; thus God's children will grow in grace.
Fourthly, is is the duty to which God's children are continually exhorted, and their activity is to consist in a striving for growth. That it is their duty is to be observed in the following passages: "But grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ" (2 Peter 3:18); "He that is righteous, let him be righteous still: and he that is holy, let him be holy still" (Rev. 22:11). The nature of this activity is expressed as follows: "Not as though I had already attained, either were already perfect: but I follow after" (Phil. 3:12). If it were not necessary for believers to grow the exhortations to that end would be in vain.
Some remain feeble, having but little life and strength. this can be due to a lack of nourishment, living under a barren ministry, or being without guidance. It can also be that they naturally have a slow mind and a lazy disposition; that they have strong corruptions which draw them away; that they are without much are without much strife; that they are too busy from early morning till late evening, due to heavy labor, or to having a family with many children, and thus must struggle or are poverty-stricken. Furthermore, it can be that they either do not have the opportunity to converse with the godly; that they do not avail themselves of such opportunities; or that they are lazy as far as reading in God's Word and prayer are concerned. Such persons are generally subject to many ups and downs. At one time they lift up their heads out of all their troubles, by renewal becoming serious, and they seek God with their whole heart. It does not take long, however , and they are quickly cast down in despondency - or their lusts gain the upper hand. Thus they remain feeble and are, so to speak, continually on the verge of death. Some of them occasionally make good progress, but then grieve the Spirit of God and backslide rapidly. For some this lasts for a season, after which they are restored, but others are as those who suffer from consumption - they languish until they die. Oh what a sad condition this is! (Chapter 89. Spiritual Growth, pg. 140, 142-143)”
Wilhemus à Brakel
The Christian's Reasonable Service, Vol. 4