Thematic Bible: Should not be made in an unknown language

For if I pray in a tongue, my spirit prays, but my mind is unfruitful. What is the outcome then? I will pray with the spirit and I will pray with the mind also; I will sing with the spirit and I will sing with the mind also. Otherwise if you bless in the spirit only, how will the one who fills the place of the ungifted say the "Amen" at your giving of thanks, since he does not know what you are saying?