God does need us to spread the good news though, He gave man the ministry of reconciliation - reconciling men unto God.
But I agree, I don't even like it when people say 'use me oh Lord', or something to that effect. We have freedom of will. God will always help direct us when we need to make a decision to do something or not, but God will never 'posses' us the way the evil one does. God wants us to walk in Love in everything we do and that includes our ministry of reconciliation. It is our will to do it though, God does not "use" us. I don't think everyone that uses that term always understands it to mean possession, but it can lead to that sort of thinking and it's easy to slip into that incorrect doctrine, so we should be careful in how we use our words. Because what if you thought "God was using you", but something very wrong happens. Do you then blame God? God forbid!!! And some people do. They will blame God as if he wanted that bad thing to happen and that is definitely heresy!
I noticed that right away and nah! I didn't like that part of it. But it's what the Catholic priests think and do.