There is a theme of a sacrifice and willingness to make sacrifices in many religious. The meaning of a sacrifice is quite trivial: a believer must give away a part of his property to get the benefit or God’s benevolence he is seeking. So to say, the meaning is straightforward. The symbolic meaning comprehended by the Seeker is that you cannot gain anything for free on your Path to the Truth. For instance, to get bliss, you must give away your sufferings, some of which you find very dear.
Some mystics make a conscious sacrifice at the price known to them only, in order to gain new opportunities in their Work. There are the ones sacrificing themselves to God in their entirety. This sacrifice gives them something that can be neither explained nor understood by those who have not done it.