For conservative, Bible-believing, Trinitarian, Nicene Creed affirming protestants, this is the battle they have been fighting since the mid-1800's. It was always a matter of degree, and when to separate from liberalizing denominations.
It just gets worse and worse. Smugly, many insensitive boors on OC.net say protestants start a new denomination any time they feel like it (and maybe among the fundamentalist and charasmaniac groups this is the case). But in reality, there are faithful people in churches with a statement or confession of faith and doctrine that the liberals and modernists have so distorted and abused that they leave and start a new denpmination to try to preserve sound doctrine.
Many, like me until 4 years ago, don't even know about Orthdooxy (so don't judge them for not converting to something they know nothing about). They are just trying to preserve the faith they know so they create a new, more conservative denomination (Missouri Synod Lutheran, Presbyterian Church in America, Episcopal under an African bishop) to get away from such heathen and pagan garbage in their ecclesiastical arrangements.
My sister's Presbyterian church is going thru this - leaving the PCUSA in the upcoming year.
When I learned about Orthodoxy, it was like "Finally, no need for a new denomination." I have been blessed to discover the one true Church that's been around for 2,000 years - rather than a couple hundred, or a century or a generation, or 20 years.
And I was and am still truly thankful to learn of this, almost "out of the blue."
So, to cradles or converts -- Never be smug, never be smug. "There, but for the grace of God goes YOU!"