The Bible prophesies that the only saints who obey the feasts of God will be saved at the end (Rev.14:1~3, 12) Which means there are still the feasts of God that we must keep for our salvation until the end.
However those who do not keep the Sabbath day and the Passover, insist that we no longer have to keep the feasts of God such as the Sabbath day, the Passover etc. because they were abolished by God, just quoting Isaiah 1:13 out of context. Is that correct ?

[ Stop bringing meaningless offerings! Your incense is detestable to me. New Moons, Sabbaths and convocations- I cannot bear your evil assemblies. 14 Your New Moon festivals and your appointed feasts my soul hates. They have become a burden to me; I am weary of bearing them ] Isaiah 1:13-14

They claim that God stopped all feasts of God on based on the verses above. However we should understand the true meaning of the verse in the context. To whom did God say ?

[Hear the word of the LORD , you rulers of Sodom; listen to the law of our God, you people of Gomorrah] - Isai 1:10

It was words given to the people like Sodom and Gomorrah who were badly corrupted and did many wicked things. We can understand that they forsook the LORD by doing evils.

[Ah, sinful nation, a people loaded with guilt, a brood of evildoers, children given to corruption! They have forsaken the LORD ; they have spurned the Holy One of Israel and turned their backs on him] Isaiah 1:4

Therefore, all offerings that they had given to God, were meaningless and detestable to God. That's why God said "Stop bring meaningless offerings" and hated festivals and appointed feasts celebrated by them. Even God didn't want to listen to their prayers.

[When you spread out your hands in prayer, I will hide my eyes from you; even if you offer many prayers, I will not listen. Your hands are full of blood;] Isaiah 1:15

Thus, their insistence based on Isaiah 1:13 is untrue! In the past, the true God's people received much blessing through the feasts of God. The same goes for today. The saint to be saved, should keep the Sabbath day and the annual feasts such as the Passover etc. according to the example of Christ. We should not forget that God's feasts and salvation are inseparable! The only church in the world that fully keeps the New Covenant, the feasts of God, is the World Mission Society Church of God.