In Titus 1:15, Paul is saying that if the Judaizers are right in teaching that impurity makes everything it touches impure, then the fact that they are Cretans and all Cretans are liars, evil, and lazy, means that according to the theology of these Judaizers, even their mind and conscience are defiled.
Ephesians 4:17-19 is not teaching about Total Depravity or total inability, but about the devastating results of choosing sin over righteousness. Paul wants his readers to put off that old way of conduct, and live their new life in the Spirit with the new man which was created by God for righteousness and holiness (Ephesians 4:22-24).
Some believe that Ephesians 2:8-9 teaches that faith is a gift of God. But the grammar and context of Ephesians 2 does not support this idea. This post looks at the context of Ephesians 2, and summarizes the five main views on what the gift of God is, before finally explaining what my view is and why.