This is a fair and reasonable question.
Most consider the world timeline the truth, and most who hear of the timelessness of God consider it one or the other, and therefore do not receive it. So, then, "It is finished" gets lumped in with the idea of the timeline of the world being correct and timelessness being foolishness. But it is both.
But, if one does not understand the one (the world in parable and the object thereof), how can they understand the other (which is the subject of the parable)?
So, God has given the parable, and I have given the interpretation as it first came from Christ. But many are turned back.