To begin with, we can never know for sure why Covid-19 happened. The reason is common sense: history only records for us that some events have happened, but it does not tell us why they happen. At best, historians can only guess at a probable reason. Our responsibility as Christians is to use the Bible to interpret why certain events probably happened. Why did the Covid-19 pandemic happen? A probable reason is that it is a judgement of God on the sin of humankind.
First, if you look at the Book of Revelation, God’s wrath in the last days against humankind will happen at a global scale. Covid-19 is global. For instance, Rev 6:8 says,
I looked, and there before me was a pale horse! Its rider was named Death, and Hades was following close behind him. They were given power over a fourth of the earth to kill by sword, famine and plague, and by the wild beasts of the earth.
The tentacles of Covid-19 have extended its reach to every nation on earth by threatening our health and collapsing our economy. Every human being on earth is feeling its sting. Also, when God punishes humankind, he often uses plagues and diseases to do so. Thus, God threatened the nation of Israel in Deuteronomy 28:
15 However, if you do not obey the LORD your God and do not carefully follow all his commands and decrees I am giving you today, all these curses will come on you and overtake you . . . 21 The LORD will plague you with diseases until he has destroyed you from the land you are entering to possess.
Second, God also has a valid reason to punish humankind. We can observe an undeniable steep slide into immorality. Many countries (Taiwan in 2019 is one instance) have legalised same sex marriage. Churches and Christian organisations have quarreled and even split over this issue. China changed the Bible to align it with its communist policies to which the Bible warns in Rev 22:18-19,
If anyone adds anything to them, God will add to that person the plagues described in this scroll. And if anyone takes words away from this scroll of prophecy, God will take away from that person any share in the tree of life and in the Holy City, which are described in this scroll.
It could be that God did not send the virus. But it is more likely that Covid-19 did not happen by chance (in fact , nothing does), but is an act of God inflicted on the world for its rampant sins. The Bible tells us to repent of our sins. Then, perhaps God will show us mercy. The cure to Covid-19 is not, as some professing Christians suggest, the taking of the Lord’s Supper. The right response to God is repentance. It is time to stop playing games with God and giving excuses for our sinful behaviour. God is merciful (Deut 30:2-3):
When you and your children return to the LORD your God and obey him with all your heart and with all your soul according to everything I command you today, then the LORD your God will restore your fortunes and have compassion on you.
Turn away from sin and believe in Jesus today. Return to your Lord wholeheartedly. God will show you kindness. Then you will once again be filled with much joy, peace, and strength even in sufferings and weaknesses (2 Cor 12:9).