Definition of church
Donovan and others:
To answer your question you must define what church is in order to say yes or no. If church is defined as the organized, institutionalized, hierarchical, business system it has become, then definitely NO, you don't have to go one of those in order to be saved. Simply working in any industry could save you then.
Jesus didn't come to create the same "order" of church that was already present in the world (hebrew or otherwise). He came to define church as a living, organic expression of spirit (energy) and that within that kind of organic church there is no hierarchy. How many times did he desribe the kingdom in terms of things natural? Trees, birds, crops, sowing and reaping, water, wind? He never once described his Kingdom (the kingdom of heaven in which you are asking about) as a hierarchical structured system where you have a leader and then you have followers. In fact, he spoke out against it. How many times did he tell his followers who were always arguing about who would be first in the new kingdom that it would not be that way in his kingdom. Some would argue, well he was a leader and his disciples were his followers. In fact, Jesus never described it that way. The writers of the texts might have (and they would have both political and monetary reasons for doing so). Jesus always said, to be first you must be last, to be greatest, you must become the least. Wasn't that his example with donning the towel and washing the disciples feet? He was showing them, there is no hierarchy here. We are all servants, we are all equal. Only God is in charge. That's it. Church is meant to be a circle always flowing, no beginning, no end. It's not a triangle with God on top, Jesus in lower corner and HS in the other corner. Nor is it in the form of a business organization chart. It's the circle of life. That's all.
So the question becomes if church is a man made structure, can you really be "saved" in it? Is it a requirement? No. Not even in the organic expression of church. The only requirement for being saved (as if that's even defined as a one time event, which its not and could take a separate post to explain) the only requirement is to "wake up" to the Spirit of God who lives in you. That's it.