Army of One:
The only "army of one" I know of that is truly an "army of one", is God himself.
Most of us mortals generally agree we can stand with a bit of help from our fellows.
That is why God placed different members within his "body"... as explained in 1 Corinthians 12.
Christian Culture:
Sometimes little axioms are passed around in Christian culture that have good intentions, but theologically... they probably aren't really the most accurate things to say.
Although it's commendable to have the conviction that "I will still follow God, even if I'm the only one"... that doesn't mean we should couch that wonderful conviction inside an axiom that is a quite unclear axiom.
I commend the OP, and ANYONE, for their conviction to stand against all odds, and be willing to stand for God, even if they are all alone.
However, if that is what we actually MEAN... maybe we should just say what we actually mean.
Conclusion:
1. There may be times we are forced, by necessity, to stand completely alone with no one beside us but God.
2. But we're never to seek that out; we're never to go seeking lonely times of trial and adversity.
3. We are to seek fellowship with other believers.
4. If we are to seek fellowship and help from other believers, and yet be willing to stand all alone with God if we must... then we should just say that. We should probably just strive for clarity, and say that thing which we actually mean. When we take up little axioms from Christian culture, we run the risk, quite accidentally, of promoting theological error simply due to confusion.
God Bless.
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