Shouldn't all Christians be speaking for God?  I think so. That's what the apostles and disciples did...the early Christians, the saints.  Yes.  But it takes work.   Lots of prayer, spiritual direction, reading Scripture, examination, humility. 

But yes we should be constantly struggling to speak for Him every day...being his lips and his arms and legs for the world, solving a lot of problems for the people He put right next to us.

"The Lord has need of these."