What did the early Christians believe about the Holy Spirit in the 1st and 2nd centuries AD? What does the historical evidence tell us? Did most Christians believe that the Holy Spirit was a Person? Did most Christians believe that the Holy Spirit was an impersonal divine "energy" or "force" or something like that? Is the historical evidence from the first two centuries conclusive or inconclusive in this regard?
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The New Testament contains a massive amount of first-hand evidence about what the early Church believed regarding the Holy Spirit. Unless that is taken as the prime source, all else will be futile. Space here does not permit quoting all the N.T. texts about the Holy Spirit, but if we consider something of what Jesus himself and some of the apostles said, that would serve as a starting-point.
Jesus explained that unless he returned to heaven, he could not send the Holy Spirit to indwell believers, to remind them and to guide them into all truth (See John 14:16-17 & 26 & 16:5-15). This indicates something about distinction between the Son of God and the Holy Spirit, and yet how they relate to each other in unity. As Jesus also said that the Holy Spirit would come to lift up the risen Christ (not point to himself), we further see how the two relate to each other.
The Holy Spirit's role is to enable people to see Jesus Christ and the Kingdom clearly - spiritually. We don't turn around to look at the Holy Spirit, for his job is to lift up Jesus Christ. Without his enabling, however, we will never grasp just who Jesus is. The first century Church knew and believed that.
In Romans chapter 8 Christians are told by the apostle Paul that it is the indwelling of the Holy Spirit that guarantees they now belong to Christ and will be with Christ in glory. Those who do not have his anointing do not belong to Christ. Yet the Holy Spirit is simultaneously called the Spirit of God AND the Spirit of Christ (verse 9). The three are bound together in unity and in action.
The Holy Spirit deals with the matter of convicting people of their sins (1 Thess 1:4 & 2 Thess 1:6-10) so is equally bound up in salvation as are the Father and the Son. The Holy Spirit also intercedes for believers when they pray, as does Jesus Christ (Rom 8:26-27 & Heb 8:6). And don't forget that Jesus warned that the only unforgivable sin is to blaspheme the Holy Spirit. He said we could be forgiven for all blasphemies except that. This proves the deity of the Holy Spirit, for only a person can be blasphemed. Ananias and Sapphira were struck dead for lying to the Holy Spirit, which was equated with lying to God, and for tempting (testing) the Holy Spirit (Acts 5:1-11, especially verses 4 & 9).
All of these truths were written down in the N.T., long before the end of the 1st century. This means that religious points about the Holy Spirit just being an impersonal energy could not have arisen within the new Church, for they were in awe of the Holy Spirit (Acts 5:11). The Apostles did warn, however, that after their departure, heresies would arise; wolves in sheeps' clothing would come into the congregations, to lead them astray. Right enough, even before the end of the 1st century, men were starting to twist what Christ and the Apostles had said. That is why it's essential to collate ALL the N.T. statements about the Holy Spirit, to spot deviations from that in history. The fact that there are different beliefs about the Holy Spirit today proves that – somewhere along the road – deceptive teachings crept in to the Church.
