Wes at Reason to Stand doesn’t think that it is. He cites the Old Testament verses that are used to support tithing and explains why he doesn’t think they are applicable to Christians.

Then he says this:

Christ fulfills the requirements of the law in the NT. So for the same reason we no longer sacrifice animals on alters or consider buildings as sacred or see the Levitical priesthood as being in effect, we no longer tithe to support a theocratic system of government.

[…]the tithe has not been reinstituted in the NT. And yes, the tithe would have to be reinstituted since in the OT the tithe was given to a specific place (the temple) to specific people (the priests) under a theocratic system or partially independent Jewish state as the case is in the NT until about 90AD when they were eliminated as a sovereign or even semi-sovereign state.

In the NT we are told that we are to give to the poor, the needy, etc. It may be the case that man-made organizations such as 501c3 non-profit businesses may do a good job of filling the needs of the poor and needy. However it is wrong to conflate the ekklesia or assembly of believers with either the temple of the OT (to which tithes were to be paid) or a building/man-made organization which is meant by most pastors who advocate tithing.

Finally, in the NT we are told that our giving should not be under compulsion and in accordance with what we’ve decided in our hearts to give per 2 Corinthians 9:7. A tithe, by contrast stands directly opposed to this sentiment as it is both compulsory (Malachi 3:8-12) and it is a specified amount (Numbers 18:26).

In the NT we are called to practice grace-based giving to those in need. While some may choose to give to organizations that can and often do meet the needs of those in need quite well, others don’t. Neither, however, are sinning in how they choose to spend their money. However it is wrong to assert that the tithe is still in effect today. Especially when what we are supposedly tithing to is 1. not the temple and 2. often horribly mismanaged and/or spent almost exclusively on infrastructure (like props for the big show on Sunday morning).

I can tell you right now that I only do targeted giving for specific events that the church holds. The rest of my giving is to specific scholars and to build up other Christians who are doing good work with non-Christians.