Paul reveals in Romans 10:9, that a person has to confess with his mouth that Jesus is Lord and believe in his heart that Jesus was raised from the dead, before he can be saved.
It is possible to be saved, yet not have what Jesus said was the baptism of the Holy Spirit. Since the Holy Spirit is now given freely and we don't have to tarry for His coming, we can receive salvation and the baptism of the Holy Spirit at the same time. But, it isn't automatic. We must ask and believe for the baptism of the Holy Spirit, just as we believed for salvation.
Speaking in tongues is unique to the Church. This is because when a person speaks in tongues, his new born-again spirit is speaking (1 Corinthians 14:14), not his mind. Before salvation, our spirit was the part of us that was, "dead in trespasses and sins." Until we received a new spirit (2 Corinthians 5:17), the Holy Spirit could not give us this supernatural communication with the Father.
There are two kinds of speaking in tongues which are clearly spoken of in 1 Corinthians 13:1. They are called "the tongues of men and of angels." The tongues of men are the known languages in which the disciples spoke. The tongues of angels, or heavenly languages, are the tongues that all Spirit-filled believers can speak, and are what Paul spoke about in 1 Corinthians 12-14.
Jesus said that the Holy Spirit would lead us into all truth and teach us all things. Receiving the baptism of the Holy Spirit is the single most important key to receiving revelation knowledge from God.
