I was thinking of 1 Cor 12:7-10. Verse seven brings up the spiritual matter of manifestations and the next three verses lists the manifestations one of which is tongues.If eternal life is a gift, and it is, then so is speaking in tongues:
"23For the wages of sin is death, but the gift (charisma) of God is eternal life in Christ Jesus our Lord." Romans 6:23
"28And in the church God has appointed first of all apostles, second prophets, third teachers, then workers of miracles, and those with gifts (charisma) of healing, helping, administration, and various tongues. 29Are all apostles? Are all prophets? Are all teachers? Do all work miracles? 30Do all have gifts (charisma) of healing? Do all speak in tongues? Do all interpret? 31But eagerly desire the greater gifts (charisma)." 1 Corinthians 12:28-31
In the end, everything we have from God is a gift. I realize that. However one of the gifts God gave us is holy spirit. The problem with much teaching that tongues is a gift, leads people to think it is a special thing, only the those who were singled out by God. That of course leads the vast majority of Christians to think they are not "special" and therefore do not have the "gift" of tongues. But that's not right. Paul, by revelation from God, said he wished every Christian spoke in tongues, so it MUST be available for all Christians to speak in tongues.
All Christians can speak in tongues because all Christians have the GIFT of holy spirit. As 1 Corinthians 12:7-10 says, there are nine different MANIFESTATIONS, one of which is tongues. In short, if you are born again, you have the GIFT of holy spirit which you, by your free will, can MANIFEST power form on high (Luke 24:49) into the material world.
Perhaps you could imagine that the devil would absolutely loose his mind if all Christians MANIFESTED that power from on high? I suspect his only answer is to keep as many Christians as possible from knowing about those MANIFESTATIONS, including tongues.
As you said, when all is said and done all of this is truly a gift . We certainly didn't earn it!