@ Absolutely -
No, it’s only an impossibility if modern tongues is read into the text.
Let’s put the passage into a more modern English, and give it a more literal translation from the Greek:
“One who speaks in a language speaks not to men, but to God; for no one hears (with understanding); in the Spirit however, he utters mysteries.”
“One who speaks in a language speaks not to men, but to God” – Yes, if no one listening to me speaks my language, I am, in effect, speaking (praying) only to God.
“For no one hears (with understanding)” Again, correct – if no one speaks my language, no one will understand what I’m saying; they will not hear me with understanding. The Greek uses ‘hear’ in this passage; the parenthetical “with understanding” is inferred.
“In the Spirit however, he utters mysteries” – Again, “praying in the Spirit” is defined as I have it in previous posts (it’s not the words being said, rather how one is praying; i.e. by the power and leading of Spirit and according to his will). So though the speaker is praying in the Spirit, he is still uttering ‘mysteries’ because no one understands his language and no one can derive any benefit from what he’s saying.
There isn’t anything in this passage that suggests modern tongues-speech; it’s just not there. It is read into the text by Pentecostal/Charismatic Christians, particularly concentrating on the idea that the speaker has no clue what he himself is saying. There’s nothing there that even remotely would suggest this. In order for modern tongues to be ‘proofed’ in the passage, i.e. in order for “tongues” to work here however, it has to and can only be understood as the speaker also has no clue what he’s saying.
The idea of real, rational language here is further supported by the very demographic make-up of Corinth itself – to suggest it’s anything else simply does not hold.
I don’t really see 1 Cor. 14:15 as a contrast. That said, I can see where tongues-speakers would due to their definition of ‘praying in the Spirit’.
1 Cor. 14:15 ties into vs. 13 and 14 and concludes with v.15.
To sort of quickly paraphrase - if you’re going to pray at a public meeting in a language no one is familiar with, make sure you secure an interpreter so that all may benefit. If you pray in your own language (one that you understand but those listening to you do not), your understanding of it will be unfruitful for others; thus, certainly pray or sing praises in the Spirit, but with understanding (for others) (there’s no “my” in these sentences), otherwise you’re giving thanks enough (to God), but no one else is benefiting from your efforts well enough so that they can join in with an “Amen”.
This whole section deals with real rational language, specifically in an environment such as Corinth where, due to the demographic make-up, everyday communication can be a challenge; let alone the complications and nuances of prayer.