In the words we have necessity of perseverance —having done all. Doctrine. He that will Christ’s soldier, must persevere to the end of his life in this war against Satan. This, having done all, comes in after our conflict with death. That ye may be able to withstand in the evil day; then follows, having done all. We have not done all till that pitched battle be fought. ‘The last enemy is death.’ The word imports as much as to finish a business, and bring a matter to a full issue, so Php. 2:12, where we translate it well, ‘work out your salvation,’ that is, perfect it. Be not Christians by halves, but go through with it; the thorough Christian is the true Christian. Not he that takes the field, but he that keeps the field; not he that sets out, but he that holds out in this holy war, deserves the name of a saint. There is not such a thing in this sense belonging to Christianity as an honourable retreat; not such a word of command in all Christ’s military discipline, as fall back and lay down your arms; no, you must fall on, and stand to your arms till called off by death
First. The necessity of perseverance, because we are all under a covenant and oath to do this. Formerly soldiers used to take an oath not to flinch from their colours, but faithful to cleave up to their leaders; this they called sacramentum militare—a military oath. Such an oath lies upon every Christian. It is so essential to the being of a saint, that they are described by this: ‘Gather my saints together, those that have made a covenant with me,’ Ps. 50:5. We are not Christians till we have subscribed this covenant, and that without any reservation. When we take upon us the profession of Christ’s name, we list ourselves in his muster-roll, and by it do promise that we will live and die with him in opposition to all his enemies. ‘Every nation will walk in the name of his god, and we will walk in the name of our God;’ and what is it to walk in the name of our God, but to fight under the banner of his gospel, wherein his name is displayed, by giving an eternal defiance to sin and Satan? If a captain had not such a tie on his shoulders, he might have them to seek when the day of battle comes. Therefore Christ tells us upon what terms he will enrol us among his disciples. ‘If any man will be my disciple, let him deny himself, and take up his cross, and follow me.’ He will not entertain us, till we resign up ourselves freely to his disposal, that there may be no disputing with his commands afterwards, but as one under his authority, go and come at his word.
Second. Perseverance is necessary, because our enemy perseveres to oppose us. There is no truce in the devil’s heart, no cessation of arms in our enemy’s camp. If an enemy continue to assault a city, and they within cease to resist, it is easy to tell what will follow. The prophet that was sent to Bethel did his errand well, withstood Jeroboam’s temptation, but in his way home was drawn aside by the old prophet, and at last slain by a lion. Thus many fly from one temptation, but not persevering, are vanquished by another; those that at one time escape his sword, at another time are slain by it. Joash was hopeful, when young, but it lasted not long. Yea, many precious servants of God, not making such vigorous resistance in their last days as in their first, have fallen foully, as we see in Solomon, Asa, and others. Indeed, it is hard when a line is drawn to a great length, to keep it so straight that it slacken not, and to hold a thing long in our hand, and not to have a numbness grow in our fingers so as to remit of our strength; therefore we are bid so often to hold fast the profession of our faith. But when we see an enemy gaping to catch us when we fall, methinks this should quicken us the more to it.
Third. Perseverance is necessary, because the promise of life and glory is settled upon the persevering soul. The crown stands at the goal, he hath it that comes to the end of the race. ‘To him that overcometh will I give,’ not in prœlio, but in bello—not in a particular skirmish, but in the whole war. ‘Ye have need of patience, that, after ye have done the will of God, ye might receive the promise,’ Heb. 10:36. There is a remarkable accent on that henceforth, which Paul mentions, II Tim. 4:7, 8 ‘I have fought a good fight, henceforth there is laid up for me a crown of righteousness.’ Why, was it not laid up before? yes, but having persevered and come near the goal, being within sight of home, ready to die, he takes now surer hold of the promise. Indeed, in this sense it is, that a gracious soul is nearer its salvation after every victory than it was before, because he approacheth nearer to the end of his race, which is the time promised for the receiving of the promised salvation, Rom. 13:11. Then and not till then the garland drops upon his head.