What is the importance of speaking in tongues? I have been told that I need to pray for the ability to speak in order to fully know God. Is this true?
In the history of the church, three views have developed about the spiritual gift of speaking in tongues. First, that this gift is an ecstatic prayer language, unintelligible to the speaker, in order to speak to God at a higher and deeper level. Second, the gift is an ecstatic prayer language that must be interpreted by another who has the spiritual gift of the interpretation of speaking in tongues, in order to speak a word from the Lord to a congregation. Third, the gift refers to the supernatural ability to speak a human language unknown to the speaker in order to make the words of God known to a human speaker of that language.
The book of Acts describes three incidents when someone was speaking in tongues (Acts 2:1–4; 10:44–47; 19:1–7). In each, the gift occurred when eyewitnesses of the gospel reached a new region that previously had not heard the gospel. The Holy Spirit used the gift of speaking in tongues to verify that this gospel message about the death and resurrection of Jesus was true. Those who heard speaking in tongues were people who had not heard the message of the gospel previously and had no witness or documents (such as the New Testament, which we have today) to verify the truthfulness of the gospel story. The use of the gift resulted in the Spirit falling upon believers from the resurrected Lord in heaven.
Nowhere in Acts or 1 Corinthians is there any teaching that the gift of speaking in tongues gives a believer deeper knowledge of God. That teaching is a later development, perhaps to justify the experiences of those who believe tongues to be an ecstatic prayer language. A deeper knowledge of God comes by grace as one humbles oneself under the truth of the Word of God with obedience, as the Spirit of God reveals more of who God is and what He does.