Summary: The enemy has used divide and conquer to split the Church/Body and he is doing it well.
"Division is devastating to effectiveness." Tim Dilena.
Division in the Body has possibly done more damage to Western Christianity than heresy. That said, we cannot unite around anything but truth.
Ten churches of like faith in a town or even ten miles away are a bar to effectiveness. Nine are redundant. It is a horrible testimony to the unbelievers and a waste of God's manpower and resources.
"Divisions in the church, always breed atheism in the world." Puritan Thomas Manton
Wonder why atheism is on the rise? Division among the true believers, not the apostates and cults. When there are 81 churches in a town of 30K and only a third of the population attend church we do not have a lack of buildings or groups. We have a sin problem that created the splits/new starts and that sin has led to at a minimum apathy and at the maximum atheism in the town. Multiply that in every town in America and it is no surprise that atheism and false religions are thriving.
Until we solve the sin of division among us, we have little hope of converting the town let alone a nation. There comes a time when you have to pull the plug on dying churches and bury the corpses of the dead ones as their decay is not a sweet savor to men.
If your church is dying there is some reason. There may have been sin in the camp. Most likely a power struggle that caused a split. In a split, there is not always a side that was right and a side that was wrong. If you cannot see the Church as His and you cannot heal the wounds there may be error or both sides. You have split the Body neither side may survive. You cannot cut a person in half and expect either side to survive.
Unless, there is no other church of like faith around there is no need to start another one. Join the other church, especially if it is thriving. There are enough monuments to ego in place, you need not build another one. You may have the gifts to make it thrive, if it is not. God's gifts have been wrongly dispersed by men.
We drive fifty miles to a job. You can do ten or more to church, if necessary. Ideally, you should serve in a church in your town as that is biblical and more effective. If you must serve in a church out of town make sure you serve your community in some way.
Psalms 133:1 A Song of degrees of David. Behold, how good and how pleasant it is for brethren to dwell together in unity!
Ephesians 4:3 Endeavouring to keep the unity of the Spirit in the bond of peace.
Ephesians 4:13 Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:
Most people apply this to unity within their building or group. This exhortation is for the Body of believers in Ephesus, the only church in Ephesus, and by extension to all Christians.
If you and your group have the Kingdom's agenda and not your own you will seek for unity and heal wounds. You would seek to merge churches of like faith to have the people of God be more effective. If not, then we will continue to see the decay of our churches, town and country.
I know of three churches in NC that have merged so it can be done. May God close all the churches that are not of Him or have gotten off mission being social clubs with no impact in the community rather than transforming their community with the Gospel. Maranatha!