For All Have Sinned

"For all have sinned...." means that, apart from Christ, we can do nothing good, nothing holy, nothing decent, nothing honorable, & nothing righteous, whatsoever. Apart from Christ, everything we do, have done in the past, and ever will do, is vile and wicked before a holy God. Apart from Christ, everything we are, were, and ever will be, is vile & wicked before a holy God.

"come short of God's glory…" means that you and I are devoid, utterly lacking, completely destitute, and absolutely inferior of any heavenly value whatsoever. Apart from Christ, we are so wretched & destitute that we are not only unworthy of being redeemed, but we are not worth a moment of God's time to consider redeeming us.