"The Spirit scrutinizes all matters, even the deep things of God. Who, for example, knows a man's innermost self but the man's own spirit within him?" (1 Cor 2:10-11) "In the synagogue there was a man with an unclean spirit" (Lk 4:33). From these Scriptures, we see that there are three kinds of spirits: God, human spirits, and angelic spirits (good angels or demons).
These three sources of spirits are the origin of everything that happens. Therefore, to understand life we need to discern the spirits behind things. This is more complicated than discerning which one of the three spirits is at work because more than one spirit can be the cause of some things. At different times, both the Holy Spirit and demons work through human spirits.
To understand reality, we need a special gift from God — the gift of discernment of spirits (see 1 Cor 12:10). Not everyone has this gift, but everyone needs it. Therefore, we must use and develop this gift if we have it, so we can serve others. Moreover, everyone, even those with the gift of discernment of spirits, needs to ask the help of others who have this gift. Without the gift of discernment of spirits, we will be confused and probably deceived, divided, and defeated by evil spirits. With the discernment of spirits, we will know God and even "the deep things of God" (1 Cor 2:10). We will know the truth about life. We will be free, peaceful, joyful, and victorious.
Ask the Lord for the gift of discernment of spirits or, if you already have it, ask for the gift to be developed. Ask the Lord to help you recognize this gift in others. Form Christian community in which this gift can be readily shared. Then follow the Holy Spirit (Gal 5:25), make holy the human spirit, and drive out the evil spirits.