Notwithstanding, God doesn't strike us dead for sinning in this New Testament Age, but, we still ought to highly regard God's Precepts and Statutes and deliberately strive to avoid the sin of complaining and all other things that God detests.

The way He relates to His people has changed, but His Character never changes and what He hates we ought to also hate and what He values we ought to value also (Ephesians 5:1-12).

Furthermore, in 1Corinthians 10:1-10, Paul teaches his Church the dangers of sin; emphasizing several sin problems in which their forefathers struggled, with the sin of complaining at the forefront.....

"16 Now Korah the son of Izhar, the son of Kohath, the son of Levi, with Dathan and Abiram the sons of Eliab, and On the son of Peleth, sons of Reuben, took men; 2 and they rose up before Moses with some of the children of Israel, two hundred and fifty leaders of the congregation, representatives of the congregation, men of renown. 3 They gathered together against Moses and Aaron, and said to them, “You take too much upon yourselves, for all the congregation is holy, every one of them, and the Lord is among them. Why then do you exalt yourselves above the assembly of the Lord?”

Furthermore, Paul expounds on this sin principle in Colossians 3:12-13 and Philippians 4:12.....

"I know how to get along and live humbly [in difficult times], and I also know how to enjoy abundance and live in prosperity. In any and every circumstance I have learned the secret [of facing life], whether well-fed or going hungry, whether having an abundance or being in need." (Philippians 4:12)

"So, as God’s own chosen people, who are holy [set apart, sanctified for His purpose] and well-beloved [by God Himself], put on a heart of compassion, kindness, humility, gentleness, and patience [which has the power to endure whatever injustice or unpleasantness comes, with good temper]; 13 bearing graciously with one another, and willingly forgiving each other if one has a cause for complaint against another; just as the Lord has forgiven you, so should you forgive." (Colossians 3:12-13)

Throughout the Israelites' long Exodus out of Egypt; (their 40 years wandering around in the wilderness) God sent His Provisions from Heaven (manna), but they still complained against Moses about God not making their journey easier and more pleasant with food they thought would be better than manna (Exodus 16:31-36 & Numbers 11:7-9). These Israelites God had named "Levites," as He set them apart to do His Work and now, these men were trying to overthrow Moses and Aaron....

"4 So when Moses heard it, he fell on his face; 5 and he spoke to Korah and all his company, saying, “Tomorrow morning the Lord will show who is His and who is holy, and will cause him to come near to Him. That one whom He chooses He will cause to come near to Him. 6 Do this: Take censers, Korah and all your company; 7 put fire in them and put incense in them before the Lord tomorrow, and it shall be that the man whom the Lord chooses is the holy one. You take too much upon yourselves, you sons of Levi!”

8 Then Moses said to Korah, “Hear now, you sons of Levi: 9 Is it a small thing to you that the God of Israel has separated you from the congregation of Israel, to bring you near to Himself, to do the work of the tabernacle of the Lord, and to stand before the congregation to serve them; 10 and that He has brought you near to Himself, you and all your brethren, the sons of Levi, with you? And are you seeking the priesthood also?

"11 Therefore you and all your company are gathered together against the Lord. And what is Aaron that you complain against him?”

12 And Moses sent to call Dathan and Abiram the sons of Eliab, but they said, “We will not come up! 13 Is it a small thing that you have brought us up out of a land flowing with milk and honey, to kill us in the wilderness, that you should keep acting like a prince over us? 14 Moreover you have not brought us into a land flowing with milk and honey, nor given us inheritance of fields and vineyards. Will you put out the eyes of these men? We will not come up!”

So, the Lord made arrangements to meet with Moses, Aaron and the rebels, but they refused saying "We will not come up!" Moreover, they complained that Moses had not yet brought them into the Promised Land.

"15 Then Moses was very angry, and said to the Lord, “Do not respect their offering. I have not taken one donkey from them, nor have I hurt one of them.”

16 And Moses said to Korah, “Tomorrow, you and all your company be present before the Lord—you and they, as well as Aaron. 17 Let each take his censer and put incense in it, and each of you bring his censer before the Lord, two hundred and fifty censers; both you and Aaron, each with his censer.” 18 So every man took his censer, put fire in it, laid incense on it, and stood at the door of the tabernacle of meeting with Moses and Aaron. 19 And Korah gathered all the congregation against them at the door of the tabernacle of meeting. Then the glory of the Lord appeared to all the congregation.

20 And the Lord spoke to Moses and Aaron, saying, 21 “Separate yourselves from among this congregation, that I may consume them in a moment.”

22 Then they fell on their faces, and said, “O God, the God of the spirits of all flesh, shall one man sin, and You be angry with all the congregation?”

23 So the Lord spoke to Moses, saying, 24 “Speak to the congregation, saying, ‘Get away from the tents of Korah, Dathan, and Abiram.’ ”

25 Then Moses rose and went to Dathan and Abiram, and the elders of Israel followed him. 26 And he spoke to the congregation, saying, “Depart now from the tents of these wicked men! Touch nothing of theirs, lest you be consumed in all their sins.” 27 So they got away from around the tents of Korah, Dathan, and Abiram; and Dathan and Abiram came out and stood at the door of their tents, with their wives, their sons, and their little children."

At this refusal, God told Moses to step aside and He consumed them (the 3 men and their families) with an earthquake.

"28 And Moses said: “By this you shall know that the Lord has sent me to do all these works, for I have not done them of my own will. 29 If these men die naturally like all men, or if they are visited by the common fate of all men, then the Lord has not sent me. 30 But if the Lord creates a new thing, and the earth opens its mouth and swallows them up with all that belongs to them, and they go down alive into the pit, then you will understand that these men have rejected the Lord.”

31 Now it came to pass, as he finished speaking all these words, that the ground split apart under them, 32 and the earth opened its mouth and swallowed them up, with their households and all the men with Korah, with all their goods. 33 So they and all those with them went down alive into the pit; the earth closed over them, and they perished from among the assembly." (Numbers 16:1-33)

Moses warns the people that God is going to cause the earth to swallow them up, therefore, he intercedes and begs God to spare them, and God killed all those that had complained against Him; "all the men with Korah."

Then God tells the congregants who were still standing to distance themselves from the rebels and sent a fire to consume the 250 who came with incense; an offering God refused to accept. Then the people murmured against Moses saying "he killed the people."

Then God told Moses He would kill all the congregation for complaining by sending a plague to their camp and 14,700 of them died.......

Biblestudyministry.com

NKJV, AMP Bible