Because we are nothing apart from Christ, but by His grace, we can do and be incredible things.
“For I am the least of the apostles and do not even deserve to be called an apostle, because I persecuted the church of God. But by the grace of God I am what I am, and his grace to me was not without effect. No, I worked harder than all of them—yet not I, but the grace of God that was with me.”
1 Corinthians 15:9-10 NIV