US pastor and author Tim Keller has shared his thoughts on megachurches and why he thinks they have "some design deficits". 

In a lengthy Facebook post, Keller said he believes megachurches are "poor places for formation and pastoral care due to their size".  

"In our current cultural moment that is a deadly problem because Christians are being more formed by social media than local Christian community. We need thick communities and the size 
of our churches factor into that."

The founder of Redeemer Presbyterian Church in New York City said the size of his congregation, among other factors, were the reasons why he decided to split his own megachurch into 
various different congregations. 

When Keller retired in 2017, the church was divided into three churches but has now grown into five separate places of worship spread across New York City. 

"We didn't just want to build one megachurch, our core vision was centered on 'to help build a great city for all people through a movement of the gospel.' Gospel movements are fueled by the multiplication of generative churches, and diverse leaders," Keller wrote on his Facebook post. 

The 71-year-old went on to say that for him, it is more beneficial to have "10 churches of 400 scattered throughout the city, rather than one church of 4,000 in the middle of it". 

He also took issue with the dependence some megachurches have on their founder. 

"Megachurches tend to grow fast under a founder, they usually depend too much on the gifts and personality of that founder so the sooner that addictive dependence is broken, the better.

"Often the founder comes to see the church as their personal possession, and an extension of their personality and self-image. They often never want to leave, nor do they know how to well. 
It is good to leave sooner rather than later as a spiritual discipline," he continued. 

Keller concluded his post by challenging megachurches to be more "nimble to the needs of those who attend and the surrounding area".