In the biblical view of the cosmos, the earth is not a planet as we know it to be. According to the Bible the earth is a flat immovable disk supported by pillars, the firmament of heaven is a solid structure (in the form of a vault on the earth) that holds back the waters above the heaven, and the stars are just lights set in the firmament and will fall to the earth in the last days. In that view of the cosmos, asteroids would not exist.
According to the Bible, God created the earth before he created the sun, moon, and stars, and he will destroy the whole cosmos in the last days when he judges the earth and its inhabitants. There are no other worlds in the biblical cosmos because there is no need or place for them. The points of light that we see in the night sky, that we know to be planets, were just considered by the Bible writers to be essentially the same as the stars, but were different in that they moved from night to night with respect to the other stars.
Jesus and Isaiah prophesied that the stars would fall from the sky in the last days. Since the stars are actually other suns like our own, which is more than 100 times the diameter of the earth, this goes to show how nonsensical the biblical cosmos is.
So you don't need to worry about an asteroid hitting the earth because of biblical prophecy. Though that is not saying it couldn't happen for other reasons.