As I talked about in Vulnerability with the Lord, we all have wounds. Some can have more intense wounds than others. But at the end of the day we are all wounded by the presence of sin within the world. Demons use these wounds that are caused either by our own sins or sins committed against us as a means to try to gain a foothold within our lives. However a demon may end up being able to afflict us and how extensively is ultimately determined by God. As many exorcists will echo "demons are on a short leash". On certain accounts of possession cases while in the process of demonic expulsion exorcists have recounted that demons have shared that Christ had limited them (the demon) only to a specific part of the person's body, and that the demon cannot go beyond what the Lord had willed for their attacks on this person. Even as His enemies the fallen angels are still slaves to the parameters set by the Divine Will.
This is why spiritual warfare, if undergone properly, can lead us further towards our sanctification. The overcoming of the battles is the richest soil for virtue. This is why we must not give in to the temptations of despair while we are being engaged by the enemy.
Demons are like a besieging army outside of the walls. They taunt from the ramparts and they surround you looking for a suitable part of your battlements to assail. They test your fortifications. If they find a weaker area of your walls they will focus their siege on that weak point, namely your vices. This is why perseverance in prayer and frequenting the sacraments available to us is crucial. We must keep the walls manned and the arrows sharp.
Not every attack of the enemy is due to a fault of the person afflicted. So spiritual warfare isn’t something that should be a cause for scrupulosity while on the defense. And on the flip side should not be a cause for despair in the sense that if an attack should come on and we have confidence that we have defended ou