So how do you know you are a "sheep", then? Your passage speaks about God's point of view, not ours.
Regards
Your question was asked of Paul and his answer is our answer,
Hold fast the form of sound words, which thou hast heard of me, in faith and love which is in Christ Jesus. That good thing which was committed unto thee keep by the Holy Ghost which dwelleth in us." -- 2 Timothy 1:12-14"For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day.
It's just so much easier than your magisterium tells you -- believe in Jesus Christ as Lord and Savior, as the propitiation for our sins, as the Lamb slain from the foundation of the world, as the reason for all existence, "by whom all things consist" (Col. 1:17).
His sheep follow Him because Christ "knows them." That's how they know they are His sheep.