Because people would think I'm not a "good Christian girl."
Which immediately reminded me of a story I heard today of a pastor who was listening to a talk about sex at a youth conference. The speaker held a rose in his hand as he was describing various sexual activities that a person can partake in (ie. sex before marriage, adultery, etc. etc.) and as he was describing them, he was ripping a petal off the rose with each description. And by the time the rose began to look damaged almost beyond recognition he held it up to the crowd and said, "now who would want that?" And this pastor wanted to stand up and scream "JESUS WANTS THE ROSE!"
That is the Gospel. I am NOT a "good Christian girl." I am a tattered, broken, defiled rose and Jesus still wants me. He still loved me and picked me up and covered me with His righteousness and gave me a new name and a new identity- His own. My acceptance before God has nothing to do with how good or bad I've been, it has everything to do with Christ and His unmerited goodness and mercy toward me.
"Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come... For our sake God made Christ- who had no sin- to become sin for us, so that in Him we might become the righteousness of God." 2 Corinthians 5:17, 21
"I will greatly rejoice in the LORD;my soul shall exult in my God,
for He has clothed me with the garments of salvation;
he has covered me with the robe of righteousness,
as a bridegroom decks himself like a priest with a beautiful headdress,
and as a bride adorns herself with her jewels.