So all the children of Israel came out, from Dan to Beersheba, as well as from the land of Gilead, and the congregation gathered together as one man before the Lord at Mizpah. And the leaders of all the people, all the tribes of Israel, presented themselves in the assembly of the people of God, four hundred thousand foot soldiers who drew the sword. (Now the children of Benjamin heard that the children of Israel had gone up to Mizpah.) Then the children of Israel said, “Tell us, how did this wicked deed happen?” So the Levite, the husband of the woman who was murdered, answered and said, “My concubine and I went into Gibeah, which belongs to Benjamin, to spend the night. And the men of Gibeah rose against me, and surrounded the house at night because of me. They intended to kill me, but instead they ravished my concubine so that she died. So I took hold of my concubine, cut her in pieces, and sent her throughout all the territory of the inheritance of Israel, because they committed lewdness and outrage in Israel. Look! All of you are children of Israel; give your advice and counsel here and now!” So all the people arose as one man, saying, “None of us will go to his tent, nor will any turn back to his house; but now this is the thing which we will do to Gibeah: We will go up against it by lot. We will take ten men out of every hundred throughout all the tribes of Israel, a hundred out of every thousand, and a thousand out of every ten thousand, to make provisions for the people, that when they come to Gibeah in Benjamin, they may repay all the vileness that they have done in Israel.” So all the men of Israel were gathered against the city, united together as one man. Then the tribes of Israel sent men through all the tribe of Benjamin, saying, “What is this wickedness that has occurred among you? Now therefore, deliver up the men, the perverted men who are in Gibeah, that we may put them to death and remove the evil from Israel!” But the children of Benjamin would not listen to the voice of their brethren, the children of Israel. Instead, the children of Benjamin gathered together from their cities to Gibeah, to go to battle against the children of Israel. And from their cities at that time the children of Benjamin numbered twenty-six thousand men who drew the sword, besides the inhabitants of Gibeah, who numbered seven hundred select men. Among all this people were seven hundred select men who were left-handed; every one could sling a stone at a hair’s breadth and not miss. Now besides Benjamin, the men of Israel numbered four hundred thousand men who drew the sword; all of these were men of war. Then the children of Israel arose and went up to the house of God to inquire of God. They said, “Which of us shall go up first to battle against the children of Benjamin?” The Lord said, “Judah first!” So the children of Israel rose in the morning and encamped against Gibeah. And the men of Israel went out to battle against Benjamin, and the men of Israel put themselves in battle array to fight against them at Gibeah. Then the children of Benjamin came out of Gibeah, and on that day cut down to the ground twenty-two thousand men of the Israelites. And the people, that is, the men of Israel, encouraged themselves and again formed the battle line at the place where they had put themselves in array on the first day. Then the children of Israel went up and wept before the Lord until evening, and asked counsel of the Lord , saying, “Shall I again draw near for battle against the children of my brother Benjamin?” And the Lord said, “Go up against him.” So the children of Israel approached the children of Benjamin on the second day. And Benjamin went out against them from Gibeah on the second day, and cut down to the ground eighteen thousand more of the children of Israel; all these drew the sword. Then all the children of Israel, that is, all the people, went up and came to the house of God and wept. They sat there before the Lord and fasted that day until evening; and they offered burnt offerings and peace offerings before the Lord . So the children of Israel inquired of the Lord ( the ark of the covenant of God was there in those days, and Phinehas the son of Eleazar, the son of Aaron, stood before it in those days), saying, “Shall I yet again go out to battle against the children of my brother Benjamin, or shall I cease?” And the Lord said, “Go up, for tomorrow I will deliver them into your hand.” Then Israel set men in ambush all around Gibeah. And the children of Israel went up against the children of Benjamin on the third day, and put themselves in battle array against Gibeah as at the other times. So the children of Benjamin went out against the people, and were drawn away from the city. They began to strike down and kill some of the people, as at the other times, in the highways (one of which goes up to Bethel and the other to Gibeah) and in the field, about thirty men of Israel. And the children of Benjamin said, “They are defeated before us, as at first.” But the children of Israel said, “Let us flee and draw them away from the city to the highways.” So all the men of Israel rose from their place and put themselves in battle array at Baal Tamar. Then Israel’s men in ambush burst forth from their position in the plain of Geba. And ten thousand select men from all Israel came against Gibeah, and the battle was fierce. But the Benjamites did not know that disaster was upon them. The Lord defeated Benjamin before Israel. And the children of Israel destroyed that day twenty-five thousand one hundred Benjamites; all these drew the sword. So the children of Benjamin saw that they were defeated. The men of Israel had given ground to the Benjamites, because they relied on the men in ambush whom they had set against Gibeah. And the men in ambush quickly rushed upon Gibeah; the men in ambush spread out and struck the whole city with the edge of the sword. Now the appointed signal between the men of Israel and the men in ambush was that they would make a great cloud of smoke rise up from the city, whereupon the men of Israel would turn in battle. Now Benjamin had begun to strike and kill about thirty of the men of Israel. For they said, “Surely they are defeated before us, as in the first battle.” But when the cloud began to rise from the city in a column of smoke, the Benjamites looked behind them, and there was the whole city going up in smoke to heaven. And when the men of Israel turned back, the men of Benjamin panicked, for they saw that disaster had come upon them. Therefore they turned their backs before the men of Israel in the direction of the wilderness; but the battle overtook them, and whoever came out of the cities they destroyed in their midst. They surrounded the Benjamites, chased them, and easily trampled them down as far as the front of Gibeah toward the east. And eighteen thousand men of Benjamin fell; all these were men of valor. Then they turned and fled toward the wilderness to the rock of Rimmon; and they cut down five thousand of them on the highways. Then they pursued them relentlessly up to Gidom, and killed two thousand of them. So all who fell of Benjamin that day were twenty-five thousand men who drew the sword; all these were men of valor. But six hundred men turned and fled toward the wilderness to the rock of Rimmon, and they stayed at the rock of Rimmon for four months. And the men of Israel turned back against the children of Benjamin, and struck them down with the edge of the sword—from every city, men and beasts, all who were found. They also set fire to all the cities they came to. Judges 20:1-48 NKJV
And about that time there arose a great commotion about the Way. For a certain man named Demetrius, a silversmith, who made silver shrines of Diana, brought no small profit to the craftsmen. He called them together with the workers of similar occupation, and said: “Men, you know that we have our prosperity by this trade. Moreover you see and hear that not only at Ephesus, but throughout almost all Asia, this Paul has persuaded and turned away many people, saying that they are not gods which are made with hands. So not only is this trade of ours in danger of falling into disrepute, but also the temple of the great goddess Diana may be despised and her magnificence destroyed, whom all Asia and the world worship.” Now when they heard this, they were full of wrath and cried out, saying, “Great is Diana of the Ephesians!” So the whole city was filled with confusion, and rushed into the theater with one accord, having seized Gaius and Aristarchus, Macedonians, Paul’s travel companions. And when Paul wanted to go in to the people, the disciples would not allow him. Then some of the officials of Asia, who were his friends, sent to him pleading that he would not venture into the theater. Some therefore cried one thing and some another, for the assembly was confused, and most of them did not know why they had come together. And they drew Alexander out of the multitude, the Jews putting him forward. And Alexander motioned with his hand, and wanted to make his defense to the people. But when they found out that he was a Jew, all with one voice cried out for about two hours, “Great is Diana of the Ephesians!” And when the city clerk had quieted the crowd, he said: “Men of Ephesus, what man is there who does not know that the city of the Ephesians is temple guardian of the great goddess Diana, and of the image which fell down from Zeus? Therefore, since these things cannot be denied, you ought to be quiet and do nothing rashly. For you have brought these men here who are neither robbers of temples nor blasphemers of your goddess. Therefore, if Demetrius and his fellow craftsmen have a case against anyone, the courts are open and there are proconsuls. Let them bring charges against one another. But if you have any other inquiry to make, it shall be determined in the lawful assembly. For we are in danger of being called in question for today’s uproar, there being no reason which we may give to account for this disorderly gathering.” And when he had said these things, he dismissed the assembly. Acts 19:23-41 NKJV
I believe one of the primary reasons believers should get together is to exhort one another. Basically, we need accountability. The Holy Spirit testifies to us who God is. When believers are around each other, they can encourage each other, admonish one another, remind one another and advise one another.
Let us hold fast the confession of our hope without wavering, for He who promised is faithful. And let us consider one another in order to stir up love and good works, not forsaking the assembling of ourselves together, as is the manner of some, but exhorting one another, and so much the more as you see the Day approaching. Hebrews 10:23-25 NKJV