Suppose you started a new job. How long would you remain employed at that job if you insisted on coming to work only when it was convenient and fit into your schedule?

And what if you told your employer that you would decide your own responsibilities while at work and how much he will be paying you? Additionally, if you didn’t feel like working at all for a year or two, you still expected a paycheck.

Ridiculous? Certainly. Since when does a subordinate call the shots? Everyone knows that the servant does the bidding of the one served. That’s self-evident.

So then why do the most people who profess worship make up their own rules when it comes to how to worship our Heavenly Father.

Yahshua said; "If you love me you will keep my commandments" This by extension means Yahweh as well. 

Yahweh's power is infinite and the trillions of stars and billions of universes obey His every command according to the physical laws he established. Nehemiyah 9:6 speaks to this. Man is the only creation of Yahweh that does not obey him. Yahweh's laws define who he is, obeying his laws defines who we are.

Knowing Who Yahweh Is

Most people don't know who Yahweh is, therefore, they sin because they have no fear of Him. Children who obey their parents have a healthy respect for their parents and fear of the consequencies of rebellion. "Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?" Romans 6:16.

Most of the time people's are driven by tradition or by what has been passed down to them. They never once think about what they are doing or if it makes sense. If men decide on their own what and how they should worship, the consequencies will be serious. Yahweh decides what is right in that regard because he controls and made all. 

Sin is doing what the Word of Yahweh commands against, such as ignoring His will. Not keeping His Feasts is sin because it transgresses the command of His law, 1John 3:4.