Ephesians 4:21-22

Surely you heard of him and were taught in him in accordance with the truth that is in Jesus.

(v21, NIV)

If you are to know Christ, there are a few different steps or aspects to take. You must first hear of him. Many people stop at this step. Some people will hear of him and that's it. Some people will hear of him and walk away, but some will hear of him and think that is enough. Hearing of Christ doesn't mean that you know him. You must be taught in him, since the truth is in Jesus himself.

You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires;

(v22, NIV)

The teaching of Christ requires a response and action from you. The teaching about Christ includes not doing what you used to do. This removal of past things is so apparent that it is described as putting off your old self. In the same way that you put on and take off clothes, you are to take off your former way of life. However, it is not simply as interchangeable as clothes, but it is described as putting off your old self. Your self is what you take off, and it seems like quite a big thing to take off. Why do you have to take it off? Well, it's being corrupted by its deceitful desires. It doesn't make sense to continue wearing something that is being corrupted. The process of corruption is continual and increasing. It'll only get worse and worse. What's also interesting is that the deceitful desires belong to the old self. So, let's say there a bunch of bees or ants that are invading your house. Maybe they're coming in from the outside, so you could seal off their entrance to your house. That would be a simple solution and then they wouldn't be able to get into your house. However, if that can't be done, then you'd have to widen the scope in order to deal with the problem. For example, you may have to simply kill all the bees or ants. Or maybe, in order to solve the problem, you'd have to move out of your house. In the same way, your old self is increasing in its corruption. The course of the problem is the deceitful desires, so a logical solution may be to cut off the deceitful desires which are the source. You can't simply separate the deceitful desires from the old self, so you must take off the old self in order to be rid of this corruption.