The New Testament mentions both speaking in tongues and praying in tongues. How are we to understand these practices?
Praying in tongues – What is it? Is praying in tongues a prayer language between a believer and God?
The first occurrence of speaking in tongues is found in Acts 2. While the 120 believers prayed in the upper room of a house, the Holy Spirit came in power and enabled people to speak in such a way that the audience who listened to them could understand their teaching in each of their languages. Similar events took place in Acts 10 and 19 as the gospel spread to Gentiles. These are the only occasions in which entire groups of people spoke in other languages as a sign of salvation coming to a new group of people.
Elsewhere the New Testament speaks of the gift of tongues as a spiritual gift (1 Corinthians 12, 14). As such, not every believer will have this ability. Many believe the gift of tongues has ceased. Those who did, or do, have the gift were to use it for the benefit of others. First Corinthians 14 also notes the importance of prophecy over tongues as it was useful for all believers.
Two important issues remain under discussion. First, what was speaking in tongues? In Acts 2 the emphasis was on the spiritual ability to speak other known languages. This was useful in evangelism, as 3,000 people were baptized as a result (Acts 2:41). Speaking in other known languages also fits the context of Paul's teaching that he spoke in tongues more than his readers in Corinth. Why? Paul spoke Aramaic, some Hebrew, Greek, and likely some Latin. God had given him the ability to communicate in multiple languages as a missionary sharing the gospel with people across the Roman Empire. While 1 Corinthians 13 mentions the language of angels, there is no reason to assume the non-intelligible language often called "speaking in tongues" is to be interpreted as an example of a heavenly language.
Second, however, is the question of praying in tongues. If speaking in tongues refers to other known languages, how are we to understand Paul's discussion of praying in tongues? Of great importance is 1 Corinthians 14:14 in which Paul mentions praying in a tongues as part of a worship gathering. This was not Paul praying by himself, but rather a discussion of prayer during a worship time with other believers. In such cases, he noted that an interpreter must be involved so others could understand. Otherwise, a person using another language should "keep silent in church and speak to himself and to God" (v. 28).
These factors help highlight that known languages are in discussion in this chapter. Paul taught that speaking other languages was an important ability, but was to be used to benefit others in the church. If this was not possible, then the person should only be using the other language alone with God.
As a result, praying in tongues is most likely not to be understood as praying in a special, non-intelligible language. Instead, praying in tongues referred to praying in another language with God that was not understood by those in corporate worship.
While there is some dispute with this interpretation, it is certainly clear that praying in tongues is not required for salvation nor is it evidence of salvation. Salvation is by grace through faith alone in Christ alone (Ephesians 2:8-9). Speaking in tongues is a spiritual gift that not all have (1 Corinthians 12).
What is the gift of speaking in tongues?
Does speaking in tongues show a person has the Holy Spirit?
What is the baptism of the Holy Spirit and when does someone receive it?
Glossolalia – What is it?
What does it mean to be filled with the Holy Spirit?
Truth about the Holy Spirit