I would say not many -----maybe this is why -----read all if interested ---just posting this part -----
https://www.blueletterbible.org/Com...y-is-the-subject-of-holy-spirit-neglected.cfm
Summary –
Why Is the Subject of the Holy Spirit Neglected?
Unfortunately, the subject of the Holy Spirit has been neglected by Bible-believing Christians. There are a number of reasons for this. We can make the following observations.
For one thing, other teachings have been perceived to be more important than the doctrine of the Holy Spirit. God the Father and Jesus Christ have been assumed to be more crucial for understanding Christian theology. Therefore, we do not study about the Holy Spirit with the same intensity.
Indeed God the Father and God the Son are often linked together in Scripture without any mention of the Holy Spirit. This is a further reason for the neglect of the study of the Spirit of God.
There has been a general neglect from the pulpit, which, in turn, has caused neglect by the people. Christians also tend to major on the minors spending more time on non-essentials than on this doctrine.
Add to this, there is also the fear of being classed as a fanatic. Since there is often much sensationalism concerning the person and work of the Holy Spirit from some segments of Christianity, others neglect to study about Him for fear of being linked with these people.
In addition, the Holy Spirit works inwardly and invisibly, which also makes Him harder to identify with than the Father figure of God or the historical person of Jesus. His mission is to speak of others rather than Himself.
Finally, there is the fact that believers do not have a personal relationship with the Holy Spirit as we do with God the Father and God the Son. His ministry is to testify of Jesus – never Himself.
Each of these factors has lead to a general neglect of the subject