2) God says we are morally responsible for what we do.
3) God is inerrant and infallible.
4) ∴ we have freedom in the libertarian sense.
I rely on Peter Van Inwagen's consequence argument to show that premise 1 is correct. It states:
If determinism is true, then our acts are the consequences of the laws of nature and events in the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us.1I think premises 2 and 3 are uncontroversial for Christian theists. Therefore, the conclusion follows deductively.
1 Peter van Inwagen, An Essay on Free Will, (Oxford: Clarendon Press, 1983), p. 56.