Jesus is Lord
This is my rough take on a series of very complex subjects. Be warned.
One of the most threatening enemies of early Christianity was gnosticism. And gnosticism was a threat for a very solid reason: it offered answers, and good ones. When people asked "why evil?", gnosticism could respond that the physical world itself was evil. In contrast, authentic Christianity could only respond with a shrug and an "I don't know".
For this reason, gnosticism never fully released its grip on the Christian mindset. Where Christianity requires a difficult balance over a dynamic tension, gnosticism rids one of mental struggles by supplying very complete answers.
At the white-hot center of the first Christian-gnostic dispute was the physicality of Jesus. Where gnosticism held that Jesus only "seemed" physical, Christianity required looking at Jesus' real, physical body as somehow being divine.
Gnosticism looked for spiritual freedom in knowledge. Specifically, gnosticism looked for freedom in arcane knowledge, hidden knowledge, knowledge that specified the hidden mapping of metaphysical beings. By having the correct metaphysical map, one could ensure they were following the right path to salvation.
There are shades of this in Christianity today. Flipping through Christian radio, I hear "Jesus is Lord" roll out endlessly. And yet I have the impression that to many of them, saying "Jesus is Lord" simply means that we have the correct name scribbled in the empty spot on our map for "ruler in the sky".
This is a far cry from what that declaration meant to early Christians. In contrast to the gnostics, the early Christians weren't challenging Zeus or Krishna or Thor for the metaphysical throne in the sky. Their challenge was far more scandalous, far scarier. They were challenging the real-world idols of Caesar and the temple.
For the early Christians, Jesus was always seen through his physical life. And his physical life led to a confrontation between himself and the forces of violence and power that ruled his world. In the crucifixion, Rome and Jerusalem had focused their entire rage and violence on shattering and destroying Jesus. And the scandalous declaration of the early Christians was that Jesus had won!
Even the resurrection, for Paul, has meaning in light of the crucifixion. Jesus had triumphed over his enemies on the cross, and the resurrection was simply the announcement of this accomplished fact.
To say "Jesus is Lord" meant that turning the other cheek was more powerful than wielding a sword. It meant that kneeling to touch a Samaritan woman was unleashing a force stronger than Caesar's grand slave squadrons. And it meant that dying on a cross was an ultimate triumph that outshone every military victory Rome and Jerusalem could boast.
This declaration of the triumph of Jesus in the physical world is dramatically different than any kind of religious claim about mapping metaphysical reality. And it's far more powerful and scandalous than the anemic declarations of religious sentiment that roll off the tongue during this time of year.