who has true faith?

Helpful distinction:

"Because of the invisible nature of saving faith and because of the complications introduced by the human capacity for inconsistency, we have no infallible way of detecting who possesses true faith in the gospel. What we can do, however, is evaluate who professes faith in the true gospel. We cannot judge the truth (reality) of their faith, but we can—and must—judge the truth (veracity) of the gospel they profess." (Dr. Albert Mohler in Four Views on the Spectrum of Evangelicalism)

Note: This is not to diminish the reality of our ability to evaluate whether or not someone's lifestyle is consistent with their professed faith (Titus 1:16; 1 John 2:4-6; 3:6; James 2:17, 24).