We sacrifice for the things that we value. When a man is in love, he will give up things and change his life around to be with his girlfriend. Sacrifice is easy when what we give is of lesser value to what we receive.
Why do we place so much value on things like education, sports, relationships, and possessions? It is because we wrap a part of our identity up in it.
I have this struggle with the sports teams that I follow. A part of my identity is wrapped up in how well they play, because I have identified myself as fan. On an irrational level I believe that my life has more value when they win, and less value when they lose.
Those types of feelings should raise huge red flags for us. When our value is wrapped up in anything other than God it is an indication of idolatry at work.
An idol is whatever you look at and say, in your heart of hearts, “If I have that, then I’ll feel my life has meaning, then I’ll know I have value, then I’ll feel significant and secure.” There are many ways to describe that kind of relationship to something, but perhaps the best one is worship.
Timothy Keller, Counterfeit Gods, p. xv
Sacrifice is one of key foundations of worship. This is especially seen in the Old Testament by the elaborate sacrificial system that was established.
The idea that sacrifice is part of worship is carried over into the New Testament. The apostle Paul wrote; I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship (Romans 12:1; ESV).
Our willingness to sacrifice and to give up things that are important to us reveals to us the value we place on things. When we value these things more than we value God means we have an idolatry problem.