I am but a dim bulb. But thanks be to our gracious LORD and Savior, there are great saints whom the LORD has blessed with wisdom from on high in matters such as these.
What follows is but a brief excerpt from a larger work by A.W. Pink entitled Tithing. I pray it answers the questions that you so earnestly seek.
The Tithe in the New testament
Only God has the right to say how much of our income shall be set aside and set apart unto Him. And He has so said clearly, repeatedly, in the Old Testament Scriptures, and there is nothing in the New Testament that introduces any change or that sets aside the teaching of the Old Testament on this important subject.
Christ Himself has placed His approval and set His imprimatur upon the tithe. "Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone" (Matt. 23:23). In that verse Christ is rebuking the scribes and Pharisees because of their hypocrisy. They had been very strict and punctilious in tithing the herbs, but on the other hand they had neglected the weightier matters such as judgment, or justice, and mercy. But while Christ acknowledged that the observance of justice and mercy is more important than tithing—it is a "weightier matter"—while, He says, these they ought to have done, nevertheless He says, these other ye ought not to have left undone. He does not set aside the tithe. He places justice and mercy as being more weighty, but He places His authority upon the practice of tithing by saying, "These ought ye to have done, and not to leave the other undone." It is well for us if we by the grace of God have not omitted justice and mercy and faith: it is well if by the grace of God those things have found a place in our midst: but the tithing ought not to have been left undone, and Christ Himself says so.
The second passage to be noted is 1 Corinthians 9:13, 14: "Do ye not know that they which minister about holy things live of the things of the temple? and they which wait at the altar are partakers with the altar? Even so hath the Lord ordained that they which preach the Gospel should live of the Gospel." The emphatic words there are, "Even so" in the beginning of the fourteenth verse. The word "tithe" is not found in these two verses but it is most clearly implied. In verse 13 the Holy Spirit reminds the New Testament saints that under the Mosaic economy God had made provision for the maintenance of those who ministered in the temple. Now then, He says, in this New Testament dispensation "Even so" (v. 14)—the same means and the same method are to be used in the support and maintaining of the preachers of the Gospel as were used in supporting the temple and its services of old. "Even so." It was the tithe that supported God’s servants in the Old Testament dispensation: "even so" God has ordained, and appointed that His servants in the New Testament dispensation shall be so provided for.
Referring next to 1 Corinthians 16:1 and 2: here again we find the word "tithe" does not actually occur, and yet once more it is plainly implied: the principle of it is there surely enough. "Now concerning the collection for the saints, as I have given order to the churches of Galatia, even so do ye. Upon the first day of the week let every one of you lay by him in store, as God hath prospered him." Now what does "laying by" imply? Certainly it signifies a definite predetermined act, rather than a spontaneous impulse, or just acting on the spur of the moment. Let us look at this again. "Upon the first day of the week let every one of you lay by him in store." (v. 2). Why are we told that? Why is it put that way’? Why use such an expression as "lay by in store"? Clearly that language points us back to Malachi 3:10. "Bring ye all the tithes into the _______" Where? The "storehouse"! That is where the tithes were to be brought. "Bring ye all the tithes into the storehouse." Now what does God say here in Corinthians? "Upon the first day of the week let every one of you lay by him in store." There is a clear reference here to the terms of Malachi 3, but that is not all. Look at it again. "Let every one of you lay by him in store, as God hath prospered him." That signifies a definite proportion of the income. Not "let every one of you lay by him in store, as he feels led"; it does not say that, nor does it say "let every one of you lay by him in store as he feels moved by the Spirit"; no indeed, it says nothing of the kind. It says, "Let every one . . . lay by him as God hath prospered him": in a proportionate way, according to a percentage basis. Now consider! If my income today is double what it was a year ago and I am not giving any more to the Lord’s cause than I gave then, then I am not giving "as the Lord hath prospered": I am not giving proportionately. But now the question arises, What proportion? What is the proportion that is according to the will of God? "As He hath prospered him." Can one man bring one proportion and another man bring another proportion, and yet both of them obey this precept? Must not all bring the same proportion in order to meet the requirements of this passage? Turn for a moment to 2 Corinthians 8:14: "But by an equality, that now at this time your abundance may be a supply for their want, that their abundance also may be a supply for your want: that there may be equality." Please note that this verse occurs in the middle of a chapter devoted to the subject of giving, and what is to be observed is, that at the beginning of verse 14 and at the end of it we have repeated the word "equality," which means that God’s people are all to give the same proportion of their means and the only proportion that God has specified anywhere in His Word is that of the tenth, or "tithe."