The tribulation would be similar to the plagues on Israel but on a much larger scale. The church is said to be persecuted ruthlessly almost to extinction, and there are judgements poured out on the world on an apocalyptic scale, and still the world does not repent.
According to Jewish and Christian scripture, the world is in total darkness at the rend times. Jesus used ruthless persecution as a word of comfort. When the world looks like it's going to hell in a handbasket, the word is to look up because redemption is coming.
To say that Christians want Armageddon is not scripturally or theologically accurate. There is a plymouth brethren theory called the pre tribulation rapture, that was embraced by baptists, and is taught at various evangelical seminaries, which supposes that the church disappears before the bad stuff mentioned above begins. Even these people don't look forward to Armageddon. They assume they won't be here then.