Tim Montgomerie, one of the founders of the Conservative Christian Fellowship, tells Premier he is concerned these changes will have a huge impact.
He was speaking after the Health Secretary, Jeremy Hunt, suggested cuts to tax credits would make Britons work as hard as the Chinese or Americans.
However David Cameron says he will continue with the reforms and says it will 'help make work pay'.
It is thought that millions of households face losing the credits from next April.
Mr Montgomerie told Premier: "You're seeing a number of tax changes, a number of benefit changes, that to me stand in contradiction to the tax credit cuts.
"The tax credit cuts will not be compensated by the welcome introduction of the national living wage, many poor families will lose a lot of money from this."
He said that the tax credit system needs to be reformed: "They do trap people in forms of dependency that ultimately aren't good for them, so there is a case to reform them.
"Some of the cuts will mean that some families are £750 worse off - some people even more - for people whose income may be £18-24,000 a year, that's a big impact.
"I think that a lot of Conservative MPs; Boris Johnson now, The Sun newspaper, David Willis - this isn't just Jeremy Corybn and the Labour party worried about these cuts.
He added that: "The basis of a good society is that everybody shares in the proceeds of good times, and shares in the austerity of bad times - and the burden is not being fairly shared at the moment."
Listen to Premier's Political Editor Martyn Eden speak to Tim Montgomerie here:
