The New Testament, in several places, refers to the phenomenon of "speaking in tongues" as a gift from God and manifestation of the Holy Spirit's power. Today, millions of Christians manifest this gift while others argue that "tongues" died out with the Twelve Apostles and no longer exists. This article is what we believe to be the correct biblical position regarding several related aspects of this subject including the difference between the Holy Spirit being "on" versus "in" someone, what it means to be filled by the spirit, and what, if anything, is the evidence of the Holy Spirit in a Christian's life.