On speaking in tongues
Something to consider: Did you know that speaking in tongues didn't proliferate until the early 1900s?!
"In most cases we are witnessing learned behavior, much the same as when a child learns to speak by consciously or unconsciously imitating sounds that he or she hears. I have heard tongue speakers repeat the same sounds every time they made an utterance to the point where I myself could imitate them. I have heard others speak in a known foreign language that corresponds to their ethnic background, and yet someone in church would interpret something they said and the interpretation would take half as much time to speak as the original utterance and they would speak in the 'first person' as if it was God himself speaking. ...Based on the negative fruit that is often associated with this gift (pride, envy, division, and confusion), what we usually see of this phenomenon is just fulfillment of 2 Timothy 4:3. Like Adam and Eve in the garden of Eden, many Pentecostal believers start out as innocent babes in Christ who are lead astray by a belief that what God has already given them is not sufficient and that they need something He has not yet given them, the so-called 'Baptism in the Holy Spirit'." - source one
source two (goes back to 1800s), source three
Pentecostals try to defend "signs" with Scripture