If the principle of tithing is so evil, why did Jacob vow to tithe of all that God gave him even 500 years before the Law was given? And, BTW, the church and temple have much in common, especially in hermeneutical principles, even in the principle of giving (cf. 1 Cor. 9:13-14). Paul says the "Lord" commanded this, so was he referring to the LORD of the OT (Gk. KURIOS, as in LXX), or Jesus Christ through some special revelation? If the former, it appears he was referring to the OT commandments given by God regarding giving to the Lord through the mode of the temple, but now applying that through the church and saying that the Lord ordained or ordered (i.e. commanded) it to be such.
Cheers, Bluefalcon