I'll add something from my experiences.
I have been attacked constantly since I got saved, because I keep my eyes on Christ. I've been attacked by Satan and his demons, and by people, non-Christians and Christians alike. And those attacks have only ever stopped if I've given in to sin or worldliness, and then gotten worse as I've surrendered to Christ again. Satan wants to keep people in bondage, and we are bringing people out of that bondage. Opening the eyes of the blind, breaking strongholds of lies, bringing light to a dark world, and we are preaching the name of Jesus which is the name that will crush the serpent wherever we go.
Ever since God put me into ministry and I at the same time started speaking God's Truth (the true Gospel) without fear to anyone who would listen, the battle got worse and worse. This seems to happen to anyone who is completely surrendering to God, but not to those who are preaching a false gospel or a half gospel, or are just church-goers who aren't really living for God at all.
There are two kinds of Christians who never gets attacked. 1. Those who are asleep spiritually. 2. The double-minded, as Dave G mentioned. Because they aren't walking in the light, but holding on to darkness. And the devil has a foothold in them and in their lives, as everyone who sins belongs to the devil. He won't attack them as he attacks you and me. Why would he? These categories of people are the ones who are the virgins without oil and the goats that Jesus never knew. They aren't surrendered to the Holy Spirit. They will be attacked once they start to come out of darkness, as the devil wants to keep them, and trials will come to them as well, but not if they stay in sin, rebellion, worldly comfort or in spiritual blindness.
Of course there are also those who are going through times of peace and rest. But if you talk to them, they will speak about their own warfare, and they will support you.
God wants to refine you. He has put a fire in your heart and He huge plans to use that fire. You are His light to this world, and the devil wants to extinguish that light. He can't, because that Light is Jesus. But God can let him try, and that fight will only add fuel to the fire. As you keep having your eyes opened to how dark and evil this world is, you will be more and more eager to spread the Gospel, and God will empower you to do so, more and more as the battle keeps raging. Do not ever believe that you are doing something wrong when you are getting attacked. It means that God is trusting you with more and more each day. Never falls for the lies that say that as a Christian we are protected, and if the devil attacks, that means God is angry because you've sinned. It could be, and we all give place to sin from time to time, and we may need chastisement to bring us back to repentance, but then God will also convict you for it. God uses trials and battles to make us stronger in Him, to increase our faith and dependance on Him, but also to increase our devotion to Jesus Christ and His Gospel. He is opening your eyes to the spiritual reality that is controlling the people living in darkness, so you will be able to relate to them much better as you minister to them. Paul knew what was going on, and so should we. But not everyone is all in for God like you are.
Keep pressing forward! It will all make sense one day!