In order to men's being true Christians, it is necessary that they prosecute the business of religion, and the service of God with great earnestness and diligence, as the work which they devote themselves to, and make the main business of their lives.
All Christ's peculiar people, not only do good works, but are zealous of good works (Titus 2:14). No man can do the service of two masters at once. They that are God's true servants, do give up themselves to his service, and make it as it were their whole work, therein employing their whole hearts, and the chief of their strength; Philippians 3:13, "This one thing I do."
Christians in their effectual calling, are not called to idleness, but to labor in God's vineyard, and spend their day in doing a great and laborious service. All true Christians comply with this call (as is implied in its being an effectual call), and do the work of Christians; which is everywhere in the New Testament compared to those exercises, wherein men are wont to exert their strength, with the greatest earnestness, as running, wrestling, fighting.
All true Christians are good and faithful soldiers of Jesus Christ, and fight the good fight of faith: for none but those who do so, do ever lay hold on eternal life. Those who fight as those that beat the air, never win the crown of victory. They that run in a race, run all; but one wins the prize; and they that are slack and negligent in their course, do not so run, as that they may obtain. The kingdom of heaven is not to be taken but by violence.
Without earnestness there is no getting along, in that narrow way that leads to life; and so no arriving at that state of glorious life and happiness which it leads to.
Without earnest labor, there is no ascending the steep and high hill of Zion; and so no arriving at the heavenly city on the top of it.
Without a constant laboriousness, there is no stemming the swift stream in which we swim, so as ever to come to that fountain of water of life, that is at the head of it.
There is need that we should watch and pray always, in order to our escaping those dreadful things, that are coming on the ungodly, and our being counted worthy to stand before the Son of Man.
There is need of our putting on the whole armor of God, and doing all to stand, in order to our avoiding a total overthrow, and being utterly destroyed by the fiery darts of the devil.
There is need that we should forget the things that are behind, and be reaching forth to the things that are before, and pressing towards the mark for the prize of the high calling of God, in Christ Jesus our Lord, in order to our obtaining that prize.
Slothfulness in the service of God, in his professed servants, is as damning, as open rebellion: for the slothful servant, is a wicked servant, and shall be cast into outer darkness, among God's open enemies (Matthew 25:26, 28). They that are slothful, are not followers of them, who through faith and patience inherit the promises. Hebrews 6:11–12, "And we desire that every one of you do show the same diligence, to the full assurance of hope, unto the end: that ye be not slothful; but followers of them, who through faith and patience inherit the promises." And all they who follow that cloud of witnesses that are gone before to heaven, do lay aside every weight, and the sin that easily besets them, and do run with patience the race that is set before them (Hebrews 12:1).
That true faith, by which persons rely on the righteousness of Christ, and the work that he hath done for them, and do truly feed and live upon him, is evermore accompanied with such a spirit of earnestness in the Christian work and course.