To be is to exist, to continue. It signifies a state.
To be steadfast is to be resolutely or dutifully firm and unwavering. It means to stand firm.
When 2 Cor. 15vs58 says ‘…be steadfast, immovable…’, it was trying to lay emphasis on the level of standing at which we should be operating. That implies there are various levels of ‘standing’ with some being more sure than the others. Some might be shaky; others might be unbalanced et cetera. The word immovable says something very important: take a firm stand such that you would be able to withstand any [and every] force trying to displace you.
A man standing on quick sand cannot be sure of his stance when compared with another man who is standing on a rock. This tells us that we need a solid ground to be steadfast. We could recount the stories of Joseph, Daniel, the three Hebrew lads, Papa Paul et al. These are men who stood their ground despite the overwhelming opposition and they were able to overcome because they had a good foothold – Christ Jesus. Papa Paul laid emphasis on this in his letter to the Colossians ‘…let your roots grow down into Him [Christ] and let your lives be built on Him. Then your faith will grow strong…’ [2vs6-8].
“…roots go down…” = depth
“…built on Him…” = base or foundation
Also, we humans have two feet which are necessary to achieve balance. You might be able to temporarily stand with one foot but you would easily fall over with the slightest push. This same analogy can be applied in the spiritual. Remember we have been warned ‘He that THINKETH he stand…’. This is a very succinct warning that reminds us that even our two feet are not enough to ensure we stand nor can they guarantee that we shall remain standing! Thus ‘…I am warning you ahead of time, dear friends. Be on guard so that you will not be carried away by the errors of these wicked people and lose your own secure footing…’ [2 Peter 3vs17]
The phrase stand firm is more like an order or a command. The Boys’ Brigade Nigeria has a very similar motto: Sure and Steadfast. It tells of total commitment. Trying to stand with just one foot is synonymous to a doubting mind: your trust is divided, so is your faith. You receive NOTHING!
Now I need to draw your attention to something very conspicuous yet which is scarcely noted: trees and leaves. Trees bud and bloom in the spring (rainy season). New leaves emerge. In the fall (commencement of dry season), we see that the trees let go of these leaves. Now the reasons are simple: the leaves are used to excrete water AND the leaves are a weight! Letting go of them ensures the tree is able to manage what little water is available as well as reducing its weight and foliage. Note that other trees also let go of their leaves, thus reducing the ‘obstructions’ to the wind-flow and this results in more ferocious and violent wind heads. In letting go of the leaves, such a tree is able to ensure that greater wind speeds neither blows it over nor uproots it.
The storms of life are seasonal and it takes determination, wisdom and understanding of the times to be able to stand firm and weather the storms.
In summary, there is no disputing the fact that we need a good dose of commitment and determination to remain steadfast. All resources need to be devoted to this task. Being on high alert. Putting on the whole amour of God.