Just because the tithe disappears with the abolition of the Levitical priesthood, that does not mean that Christians can or should low-ball the church in their giving. (That being said, I also think it’s somewhat goofy to claim that while God only claimed ten percent in the Old Testament that he claims “all of it” in the New Testament. God claimed everything in the Old Testament as well as in the New, Dt 8.18, 1 Chr 29.12,14, 16.)
Financial offerings in the New Testament must fulfill the same important functions that tithe fulfilled in the Old Testament – in particular, paying pastors and providing for the needy. (Keep in mind that needy people received significant help in ways other than by the tithe in the Old Testament.)
I think the NT Scriptures are pretty clear in regards to both sets of people. Here are some passages:
“The one who is taught the word is to share all good things with the one who teaches him” (Gal 6.16).
“The elders who rule well are to be considered worthy of double honor, especially those who work hard at preaching and teaching. For the Scriptures says, ‘You shall not muzzle the ox while he is threshing,’ and ‘The laborer is worthy of his wages’” (1 Tm 5.17-18).
“The Lord directed those who proclaim the gospel to get their living from the gospel” (1 Co 9.14).
“I have received everything in full and have an abundance; I am amply supplied, having received from Epaphroditus what you have sent, a fragrant aroma, an acceptable sacrifice, well-pleasing to God” (Phil 4.18).
“Instruct those who are rich in this present world not to be conceited or to fix their hope on the uncertainty of riches, but on God, who richly supplies us with all things to enjoy. Instruct them to do good, to be rich in good works, to be generous and ready to share, storing up for themselves the treasure of a good foundation for the future, so that they may take hold of that which is life indeed” (1 Tm 6.17-19).
“Our people must also learn to engage in good deeds to meet pressing needs, so that they will not be unfruitful” (Titus 3.14).
“Do not neglect doing good and sharing, for with such sacrifices God is pleased” (Heb 13.16).
“He who steals must steal no longer; but rather he must labor, performing with his own hands what is good, so that he will have something to share with one who has need” (Eph 4.28).
“Pure and undefiled relgion in the sight of our God and Father is this: to visit orphans and widows in their distress, and to keep oneself unstained by the world” (Jas 1.27).
“If a brother or sister is without clothing and in need of daily food, and one of you says to them, ‘Go in peace, be warmed and be filled,’ and yet you do not give them what is necessary for their body, what use is that?” (Jas 2.15-16).
“Be devoted to one another in brother love . . . contributing to the needs of the saints, practicing hospitality” (Ro 12.10, 13).
“Your prayers and alms have ascended as a memorial before God” (Acts 10.4).
“Be hospitable to one another without complaint” (1 Peter 4.9).
“Do not neglect to show hospitality to strangers, for by this some have entertained angels without knowing it. Remember the prisoners, as though in prison with them, and those who are ill-treated, since you yourselves also are in the body” (Heb 13.2-3).
“For the ministry of this service is not only fully supplying the needs of the saints, but is also overflowing through many thanksgivings to God. Because of the proof given by this ministry, they will glorify God for your obedience to your confession of the gospel of Christ and for the liberality of your contribution to them and to all, while they also, by prayer on your behalf, yearn for you because of the surpassing grace of God in you” (2 Co 9.12-14).
“For I was hungry, and you gave me something to eat; I was thirsty, and you gave me something to drink; I was a stranger, and you invited me in; naked, and you clothed me; I was sick and you visited me; I was in prison, and you came to me” (Mt 25.35-36).
“Whoever has the world’s goods, and sees his brother in need and closes his heart against him, how does the love of God abide in him?” (1 Jn 3.17).
So even if the tithe is no longer binding, the Scriptures nonetheless clearly call the Christian to support their pastors and to be generous toward the needy.