Praize said:
I have been told by some ppl that the bible says the gift of Tongues is specifically for speaking in foreign languages and that the book of Acts doesnt mention anything about an intimate dialogue/form of worship that only God can understand.

I am a strong believer in the Charismatic gifts of the HOly Spirit and am asking for advice on how I can answer this question the next time its brought up.
First I would ask them to prove their statement specifically for speaking in foreign languages
Second Acts does state that they {the Apostles} were speaking the wonderful works of God.
Third: most of the clarification on SIT is located in I Corinthians chapter 14. This gives us the explanation of when it should be used in meetings /w interpretation etc.
Several threads in this section contain much information on SIT that would be of value to you.
I have posted before, a list of some of the benefits to speaking in tongues, this may be helpful in stating your case; as follows.
Interestingly enough God uses two different words for the word another in verses 8-10 of I Cor.12. The use of these two Words shows a distinction of the
profit on two of the 9 manifestations that are specifically for the profit of the individual only;
speaking in tongues and
faith {believing}. The other manifestations are designed to profit the individual as well as others.
Tongues Benefits
1.
To speak the wonderful works of God
Acts 2:11
Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.
2.
To magnify God
Acts10:46
For they heard them speak with tongues, and magnify God.
3.
To give thanks well
I Corinthians 14:17
For thou verily givest thanks well, but the other is not edified
4.
To bring a message from God {when interpreted} I Corinthians 14:5, 27, 28;
5:
except he interpret, that the church may receive edifying.
27:
If any man speak in an unknown tongue, let it be by two, or at the most by three, and that by course; and let one interpret.
28:
if there be no interpreter, let him keep silence in the church; and let him speak to himself, and to God.
5.
Sign to the unbelievers I Corinthians 14:22, Mark 16:17;
I Corinthians:
Wherefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not, but for them which believe.
Mark:
And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;
6.
To edify you, build you up. I Corinthians 14:4, Jude 20;
I Corinthians:
He that speaketh in an unknown tongue edifieth himself; but he that prophesieth edifieth the church.
Jude:
But ye, beloved, building up yourselves on your most holy faith, praying in the Holy Ghost
7.
To speak to God mysteries {divine secrets}
I Corinthians 14:2
For he that speaketh in an unknown tongue speaketh not unto men, but unto God: for no man understandeth him; howbeit in the spirit he speaketh mysteries.
8.
Makes intercession for us
Romans 8:26&7
26:
Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered.
27:
And he that searcheth the hearts knoweth what is the mind of the Spirit, because he maketh intercession for the saints according to the will of God
Ephesians 6:18 Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints;
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God bless
sandman