The taboo word 'tithing' is making a come back in some churches. For a while it was best thought of as an unspoken principle and at worst legalism to be shunned. Now churches and Christian teachers are regaining their confidence in teaching the principle of giving a proportion of your income.

However many students and those on low income often ask how much they should be earning before they start to tithe. Should you have a full-time job before you start to tithe? Should you be able to afford your own rent before you start to tithe? Should you tithe if you are living on a student loan or a loan from your parents? At what point in our lives and careers should we begin giving back?

The principle behind this question is one that cuts to the core of tithing itself and fundamentally misunderstands it. Giving a set proportion of what you have is not based upon the idea of giving back to society when you are ready to do so. It is not based on contributing to your community if you can. It is about realising that everything you have is firstly God's, not your own.

When the Lord gave the Israelites the law on how to live well, the book of Leviticus ends with a command to tithe. God's people were told to "tithe of everything from the land," and a "tithe of the herd and flock." Leviticus 27:32 says "every tithe...will be holy to the Lord." In other words God ended his instructions for a good life with a reminder to give back to him.

Then the prophet Malachi later told the Israelites that their failure to tithe was effectively stealing from God. "'You are robbing me,'" the Lord says in Malachi 3:9. "'Bring the whole tithe into the storehouse, that there may be good in my house. Test me in this' says the Lord Almighty, 'and see if I will not throw open he floodgates of heaven and pour out so much blessing that there will not be room enough to store it.'"

So God does not invite us to tithe out of our own generosity. He invites us to tithe because of His generosity. We do not tithe only when we feel like we have something to give back. Rather not to tithe is robbing God of what is rightly his in recognition of the fact "the earth is the Lord's, and everything in it, the world and all who live in it" (Psalm 24). In other words, giving is just giving back what is already God's.

So going back to the original question, asking how much we should be earning before tithing completely misses the point. Because everything we have, no matter how much or little belongs first and foremost to God. Everything we own is God's so the question is how much do I keep for myself. There isn't a certain point at which it becomes 'sensible' to start tithing because nothing we have is really ours.

So how does this work practically?

Tithing is a great practice to get into; giving a bit each time we receive something, whether a payment, a loan or a gift, giving a bit away each time is a brilliant way of reminding ourselves that everything is God's and of His goodness in giving us anything at all.

I used to resent my Dad because when I was little we had to tithe a proportion of our pocket money. So, aged 8 I got 80p pocket money and 10p went in the church collection! It was so ridiculous and I used to get so irritated by it but looking back it was a great habit to start early on.

Get into the practice of giving a proportion of your income and treat it as a way to get you started. Tithing is an excellent floor but a bad ceiling. Don't use it as a limit to how much you give but a launchpad to start from.

So however much or little you earn, let's accept God's invitation into his adventurous experiment:

"'Test me in this' says the Lord Almighty, 'and see if I will not throw open he floodgates of heaven and pour out so much blessing that there will not be room enough to store it.'"