Let me give you the rest of what my answer would be, and that is this:
I don't see any of the things he mentioned as being impossible; in fact, several of them were clearly being practiced in NT times, which means he would be mixing hyperbole with reality back and forth, which makes for a very confusing argument to follow.
But let me get the passage again:
13 Though I speak with the tongues of men and of angels, but have not love, I have become sounding brass or a clanging cymbal. 2 And though I have the gift of prophecy, and understand all mysteries and all knowledge, and though I have all faith, so that I could remove mountains, but have not love, I am nothing. 3 And though I bestow all my goods to feed the poor, and though I give my body to be burned, but have not love, it profits me nothing.
Ok,
1.
Speaking with the tongues of angels: In question, hence the discussion, but one I think is fully possible, based on the context.
2.
Having the gift of prophecy: This one can hardly be disputed was real, and being practiced by the New Testament church.
3.
Understand all mysteries: This is another one that is hard to dispute wasn't going on in NT times. Paul made mention of understanding the mysteries of God numerous times, and nearly always in the affirmative. Here would be a couple links:
What are Paul’s Mysteries of God?
Seven Mysteries Revealed to Paul
4.
Have all faith to move mountains: Now this one is where you would seem to maybe have an argument, cuz this is talking about serious faith here. But was he talking about something that was impossible? He commanded Peter to walk on water, and during roughly the same time period taught them, "If you have faith, you shall say unto this mountain, 'Be removed and be cast into the sea,' and it will obey you."
5.
Give all my goods to feed the poor: Another one that doesn't seem to be hyperbole. Acts says many were selling their property and distributing to the poor so that the early church had all things common, and Jesus also told the rich man, "Go, sell what you have and give it to the poor, and come follow me," and then mentioned how hard it was for the rich to enter the kingdom of God to His disciples, meaning He was serious.
6
Give my body to be burned: All the apostles including Paul did indeed eventually die a martyr's death, except John. I think he is referring here to giving one's life in service to God until one eventually has to pay the ultimate price for it.
Gonna step out for a bit. I'll check back later.
God bless,
- H