That fire and speaking in tongues was a sign of judgment to the unbelieving Jews. The fire in Matthew 3 and Luke 3 is judgment. The context makes this more than clear.
Isaiah 28
For by people of strange lips
and with a foreign tongue
the Lord will speak to this people,
[SUP]12 [/SUP] to whom he has said,
“This is rest;
give rest to the weary;
and this is repose”;
yet they would not hear.
[SUP]13 [/SUP]And the word of the Lord will be to them
precept upon precept, precept upon precept,
line upon line, line upon line,
here a little, there a little,
that they may go, and fall backward,
and be broken, and snared, and taken.