This matter of giving is treated in a quite altogether different way in the NT than in the OT. In the Old Testament, the people of God where in a relationship of Law with God in a formal way. And for the support of the religious system given to them by God they had to give a 10 per cent of their earnings to support the Levites, who had to give a 10 per cent to support the priests. The priests, however, were NOT enjoined to give 10 per cent, but they were welcome to give free-will offerings to God. Of course, both the people and the levites could also give free-will offerings to God BESIDES the legal stipulation of the 10 per cent.
What is the situation for us Christians? "Of grace have ye received, give of grace". Nowhere in the NT we see that we should give by legal obligation a 10 per cent, but we are enjoined to realize that:
1) We are not our own. All that we are and all that we have are God's. We are not supposed to part with a 10 per cent and keep a 90 per cent for our own enjoyment, but to realize that all that we are and have is consacrated to God IN A REAL WAY. We are all priests unto God. That is why, different from the common people of the OT we are enjoined to free-will offerings, because the (imperfect) type of what we are is the priesthood of Israel. So, we are consacrated in what we are and what we have entirely to God. That sounds like much more encompassing than a mere tithe, doesn't it?
2) We are not under the constraints of law, but in the bonds of that mercy and grace that gave all for our salvation. God gave His Son. We are wholly His ...
Wherever we go to the Epistles for instructions, in the matter of giving we are exhorted to give with simplicity, with liberality, and with gladness. The free-will offering of hearts that have come to know the great Giver and that are learning to conform themselves to the Character of Him who is our Father, and of the Son, the Lord Jesus, who loved us and gave Himself for us. A good example is found in 2 Corinthians 8:1-5:
Moreover, brethren, we do you to wit of the grace of God bestowed on the churches of Macedonia; How that in a great trial of affliction the abundance of their joy and their deep poverty abounded unto the riches of their liberality. For to their power, I bear record, yea, and beyond their power they were willing of themselves; Praying us with much intreaty that we would receive the gift, and take upon us the fellowship of the ministering to the saints. And this they did, not as we hoped, but first gave their own selves to the Lord, and unto us by the will of God.
Best regards in our Lord Jesus,
doulos