Stromata

Eldest son and I were talking about Pentecost this morning, what it's significance was, etc. It's my opinion that, with the gift of the Holy Spirit, the apostles and disciples really had Christian faith for the first time. There are all sorts of problems with that - Peter's confession at Caesarea Philippi, to mention just one thing. But then, in the Gospel this morning, came John 7:39 - "Now this he said about the Spirit, whom those who believed in him were to receive, for as yet the Spirit had not been given, ...."  What kind of "belief" did the disciples have pre-Pentecost? Can saving faith exist without the presence of the Holy Spirit?