1 Sam 2:17

Thus the sin of the young men was very great before the LORD, for the men despised the offering of the LORD. NASB

As the time of the Judges was drawing to a close, Eli was judging Israel and was the high priest. He was a good and Godly man, but his sons were not. Though they surely knew about the LORD and His commands, they lived a life as if they didn't. Despite this, they were priests in the tabernacle of the Lord due to their birth. They were supposed to be ministering to the LORD and be representatives to the people of God's character and love, but they used their position to take advantage of the people and lived selfishly and in the flesh. 1. Samuel chapter 2 says that God saw this and it bothered Him very much. Why? Because they served God without faith and didn't care about what they were doing. Though they were priests of God, they managed His service as if it didn't matter to them. Worse then this, they bullied, abused, and threatened the honest worshipers of God. God does not want us to forget that He is primarily a holy, good, and just God and that each of us is a representative to the world for Him. Yes, God is love, and that doesn't change based on how faithful or unfaithful we are to Him, but He is also holy and desires that people see Him as He actually is. When we forget that and take lightly the things of God, we commit the same sin as Eli's sons; hypocrisy and misrepresenting God to the people. This doesn't please the Lord at all. We should strive to always honor and sanctify the things of God so that His name is glorified, both in our actions and for the example of those around us. We should seek to always worship and serve the Lord from our hearts and love and honor those we serve as Christ would. Then, God is honored, people are blessed, and God is pleased.