Obsession and addiction often go together: we tend to get obsessed with whatever we’re addicted to, and can't stop thinking about it. Intrusive thoughts are also in this category - we don’t want them any more than we want an addiction, but by their very nature, they dominate our thoughts, and thus become an obsession.

All of these have a common origin. 

All Obsessions Start With Something Good, and then Twist It

Evil defines itself by the absence of God, just as darkness defines itself as the absence of light. Satan cannot create anything; all he can do is pervert something that God made, and intended for good. 

So if evil itself is an inversion of something created to be good, then nearly everything 

God created for our pleasure and enjoyment can also become evil, or sinful, if we make it our highest aim or focus. 

Obsessions and Addiction are Placing Anything Before God

God's very first commandment to the Israelites in the Old Testament was to have no other gods before Him (Ex 20:3). The Israelites broke this commandment over and over in a very literal sense, worshipping false gods first that they'd grown up with from Egypt, and then the false gods of the nations they encountered in the wilderness and in the surrounding nations of the Promised Land. 

Today, most of us don't literally worship false gods, per se (though that's becoming more prevalent too). Rather, we make some desire or worry or need or love the focus of our lives, instead of God. 

C.S. Lewis wrote that romantic love (a very common substitute for God) "ceases to be a devil only when it ceases to be a god." The same would go for any other positive good that God created for our benefit--all could become something we seek after, more than we seek after God. That's really a prerequisite for any obsession or addiction. 

Jesus told us that if we'd seek Him and His kingdom first, everything else would be added to us (Matt 6:25-34). That's not just our needs, either. God is the giver of every good and perfect gift (James 1:17). If we make Him our primary delight, we'll get the desires of our hearts thrown in (Psalm 37:4). If we're abiding in Him first, we can ask whatever we desire, and it will be done for us (John 15:7). That's what it means, that if we find our lives (make that our primary focus), we'll lose it, but if we lose it for His sake, then we'll find it (Matthew 10:39).

The problem is, most of us don't actually believe that. 

One of my favorite fictional stories is the Superman myth. It's such a clear parable. (Also, apparently the creators of Superman were Jewish, not Christian, but they based the character of Superman on Moses and Samson of the Old Testament, as well as the prophecies of the coming Messiah. Some of the earlier Superman movies were conscious of the Christ symbolism, as well.) Lois Lane fawns over Superman, while ignoring Clark Kent—not realizing that Superman remains elusive to her only because it's clear that she doesn't really love him; she only loves what he can do for her. If she'd only choose Clark, she'd get Superman thrown in.

I think God is exactly like that. He loves us, and He longs to bless us (Psalm 103:1-5), but He wants our hearts, not our actions. He wanted a relationship with Israel, after bringing them out of the wilderness--but they were afraid of Him, and asked Moses to just be His mouthpiece and relay to them what He said (Ex 20:18-19). Even after that, God asked Moses to take seventy of Israel's elders and bring them a little way up the mountain so that they could eat and drink in His presence--even though He was at a distance, He wanted them to catch a glimpse of Him (Ex 24:9-11). He wanted to have dinner with His family. God later made this part of how the Israelites were to worship: they were to bring all their burnt offerings, sacrifices, tithes, and heave offerings of grain to the place of worship, and eat it together in His presence (Deut 12:5-7). He blessed them with increase, and as their act of worship, He wanted them to have a big feast and enjoy it. All He asked was that they invite Him to the party! 

Understanding how much God loves us is really the key to faith--faith works though love (Gal 5:6). If we don't understand how much He loves us, we aren't going to trust Him to take care of us and meet our needs (Isaiah 26:3). That's why we'll try to take matters into our own hands, attempting to meet our own needs (as an anxious primary fixation—not as the side benefit of doing our work well for the purposes of glorifying God, Col 3:23-24). But if we do truly put God first, it’s the antidote to all anxiety, addiction, and obsession.

Willpower ("The Law") Won't Work. That's the Whole Point.

Paul describes in Romans 7:14-24 what happens when we try to suppress or control any obse