The second seal opened
Rev 6:3 And when he had opened the second seal, I heard the second beast say, Come and see.
Rev 6:4 And there went out another horse that was red: and power was given to him that sat thereon to take peace from the earth, and that they should kill one another: and there was given unto him a great sword.
A man on a red horse. Red reminds us of blood and death. This was a man or a spirit loosed by God, God allowed satan to loose it. The Holy Spirit brings peace, so by this time the church may have been removed. The Holy Spirit and the church restrains death and destruction.
2 Th 2:7 For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way.
The man with the red horse removes peace, the result is that people will kill each other. There was given unto him a great sword, to bring war and strife. That spirit is already released in Islam, but it will be even worse when the antichrist comes. He comes to bring peace, he has all the world under submission, then he makes war with God's people Israel.
The work of the devil, the thief.
John 10:10 The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly.