There are two distinct layers of fear in "Journey of the Magi." First, there's the Magus-as-character fear – the kind that's pretty easy to identify by the end of the poem. And then there's the kind of fear that that first kind implies. Now before you go asking yourself what in the world Shmoop's babbling on about, allow us to explain: by making the Magus a character that's super wary of spiritual change, Eliot's secretly telling us about his own fears surrounding his recent religious conversion. After all, Eliot grew up with no real spiritual upbringing, and even though his conversion to Anglicanism was certainly his choice, that doesn't necessarily mean it was an easy one. Which is maybe why fear comes out with guns a-blazin' in this poem.
The Magis' fear in "Journey" is a specific and poignant example of our fear of the unknown. But that's all it is.
A large part of the Magis' fear in "Journey" is directly tied to an impending loss of political power. They're just washed up old dictators, trying to stay relevant.