Satan entered into heaven
The stars of God typify the people of God. Once Satan took his seat in the churches (temple – see 2 Thessalonians 2:3,4) it was as though he had entered into heaven – in order to "be like the Most High". The verses below give us some information about "war in heaven" – pointing to the churches.
Isaiah 14:13 For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north:
14 I will ascend above the heights of the clouds; I will be like the most High.
15 Yet thou shalt be brought down to hell, to the sides of the pit.
Compared to:
2 Thessalonians 2:3 Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
4 Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.