As a matter of fact, angels ARE limited by both space and time. Anything that has a beginning is bound to time.
But you’re right in that ANYTHING that has a beginning, be it angels or our souls, are not eternal.
This is what makes John 3:16 so special. Though bound by time, we’re offered by Christ the chance to be drawn up into the life that God has by nature.
When I tihnk of time and space I think of the physical universe, material reality. Things of matter, material things take up space, or exist in some space within the same dimension. If you and I are in a room, you take up space and I do. So does the furniture. We can not be in the same space, or walk though walls that take up space. I can move the furniture, but not be in the same space as the furniture. The walls, roof, furniture and me are bound by gravity and do not float off or around in space. Cars and galaxies can crash or collides into one another and there is some impact, because they can not take up the same space. Spirits are different. They go through walls, or water or air.
When Jesus cast the demon spirits out of the demoniac, they went into the herd of swine. The spirits were in the man and left and entered the swine herd. The spirits were in the pigs then, in the space where the pigs dwelt and drove them off the cliffs.
My soul is constrained to being in the same space that my physical mortal body fills in time. I can not be in your body, in the space where your body and soul reside, at the same time you are in that space. For me to take up that space, you have to move out of it, but apparently another type of being can also reside there with you, another spirit not subject to the limitations that I am.
Here in this dimension where we live mortal lives in our bodies we can change. The condition of my soul can be one way today and different tomorrow. Change presumes time, a before and after. I can be in the state of grace today and mortal sin tomorrow or vice versa. My body also can change. I can be healthy today and sick tomorrow, or vice versa. When my body dies my soul becomes fixed. It remains in the state it is in at the time of my death, either in the state of grace or without grace. In other words, I can repent of my sins here in time, but that change becomes impossible once I leave time and receive my eternal judgement.
There is a lot of mystery in this that we can not grasp.
We say God is unchangeable, immutable. We are the objects of His mercy. God is merciful. We are not eternal. We had a beginning. God is pure act. There is no potency in God. What He is, He is eternally. God is merciful to His creatures who all have a beginning. God therefore became merciful. God therefore changed. Change presumes time, a before and after.
Once again; that which is infinite and eternal can not change. Yet God became merciful. That which is infinitely great can not become greater. We receivers of mercy glorify God in His mercy. God can love Himself or know Himself and we can grasp the Trinity in this way, but He can not be merciful to Himself. He does not need mercy. We creatures do. We sinners who have a beginning do. The immutable One, became merciful. He who can not change, changed. In order for there to be change there has to be time, a before and an after. If God changed in becoming merciful He is in time, but the eternal can not be in time.
Why does God have mercy on us? He pities us. Why does He pity us? We are helpless. We are defenseless. We are wounded and sore and in pain. We suffer. We are crushed by the power of sin and evil and can not escape its slavery. He pities us, because we are weak and have no defense unless He becomes our savior. God is moved to pity by our sad plight.
God is omnipotent, all powerful. He is the unmoved mover, the source and beginning of all things, the giver of life and almighty creator. We creatures are powerless to escape the bondage of sin. We are helpless to help ourselves. We rely on God for our help. Our plight causes God to be moved. By His power, out of pity, He sets us who are powerless free.
The powerless moved the All Powerful. The most pitiable, weak, helpless, powerless, inglorious creature, moves the All Powerful.