Instead of me giving a certain amount of my support each week, if I was a gospel preacher asked the church to reduce what they give me for support in accordance with the amount I have been giving each week the past few months and not manually give, do you think that would be unscriptural?
One of the things I noticed from my studies of the Old Testament is that the Levites, who were supported by the tithes gathered in Israel, were still expected to tithe. "Speak thus to the Levites, and say to them: 'When you take from the children of Israel the tithes which I have given you from them as your inheritance, then you shall offer up a heave offering of it to the LORD, a tenth of the tithe"" (Numbers 18:26). Nor were the priests exempted from this. "And the priest, the descendant of Aaron, shall be with the Levites when the Levites receive tithes; and the Levites shall bring up a tenth of the tithes to the house of our God, to the rooms of the storehouse" (Nehemiah 10:38).
The New Testament does not have a distinct priestly caste. Instead, all Christians operate in the role of priests for the world (I Peter 2:9). While some Christians serve as preachers and are paid for their service (I Corinthians 9:14), there is no indication that they are treated differently from other Christians. They are still members of a local congregation. They still worship with the rest of the saints. And thus, they would be expected to give as they prospered, just like every other Christian (I Corinthians 16:1-2; II Corinthians 9:6-8).
"Let no one despise your youth, but be an example to the believers in word, in conduct, in love, in spirit, in faith, in purity" (I Timothy 4:12).
I guess the question I have is, not whether or not a preacher is to give, but rather, for example, if I have been giving a $100 per week and ask the brethren to reduce my support $100 per week, I am still giving. Would it be wrong for me and the church to do that? One thing about that bothers me is that when other members can't help but notice that I would not be "mechanically" giving, it would exhibit the wrong example and influence.
That is why I quoted the verse about being an example. Having your pay reduce isn't really giving as you prospered. Instead, you are asking to not prosper as much. Yes, it will make a difference in the amount of taxes you pay to the government, but that is life.