One of the things Jesus never actually said was, "By the way, now that I've introduced grace into the equation, no one needs to worry about tithing anymore."
Tithing is considerably less popular than words like generosity or sharing. Among lay people the most common question associated with tithing is: "Am I supposed to base it on net income or gross?" Among pastors the question is: "Isn't tithing an Old Testament concept? Aren't we under grace now?"
This question more or less assumes that it was only post-Pentecost that the church discovered that God is the owner and that people are stewards. It implies that legalistic old Israel thought all they had to do was check the "I tithed" box and then got to spend the rest however they wanted (ignoring biblical statements like "The earth is the Lord's and the fullness thereof").
Worse—a certain looseness of thought about grace sometimes becomes a rationale for not giving at all. A friend of mine made the case: "If my kids are really the Lord's, then I can count the money I spend on their food and clothing and college tuition as falling into the 'good steward' category. If I use my home for hospitality and hosting small group, then the same goes for furniture acquisition and home makeovers. I use my computer for Bible study and my phone to store worship songs, so those items are stewardologically deductible." This type of "all-grace giving" where we give "everything" to God looks suspiciously similar to giving nothing to God.
What if tithing is actually one of God's great gifts to us? What if tithing isn't opposed to grace, but is actually a vehicle ...