Dear Melissa,
I'm also a Christian and a crossdresser. And like you, I've felt guilt, shame, and fear about crossdressing. In my early years I received no real support or acceptance from anywhere, and it really hurt!
I've found two answers that really work (for me) for the problem of the Old Testament vs. crossdressing. I work them actively, together. I can't say that today I'm free of guilt, but I"m working on it.
Here's what works best for me...
1. We're not under law, we're under grace. The Old Testament Law prescribed a lot of details of day-to-day life. It told people not to eat meat and milk at the same meal, and not to wear mixed-fiber clothes. It told people how to deal with a house infested with mildew (pray and if that doesn't work, tear the house down.)
The Law was not necessarily consistent. The Israelites were told to kill off the Gentiles in the Holy Land--the Philistines, Canaanites, and so on. They were also told that when they slaughtered a cow, they could only eat the front half. The rest of the cow had to be sold to Gentiles. But where were the Gentiles supposed to be if they had been killed?
For us, the New Testament has set aside the Law. It has been fulfilled by the Righteous One. We don't have to follow it any more. Rather we're under grace, which means to love God above all, and to love our neighbors as ourselves. It's all about love. The Old Testament laws that aren't direct expressions of love have become historical commentary. So just as we don't keep kosher, we don't have to keep this law.
2. God's strength is made perfect in weakness. The apostle Paul quotes Jesus to this effect and it explains why everyone is not born perfect or made perfect by their walk of faith. Our weaknesses and imperfections are often intended to show the love, the majesty, and the perfection of God. God can and does work every day with imperfect people. God can do great things with us, imperfect though we still are. War heroes may sleep with teddy bears, great historical figures may have mistresses, a famous musician may be gay. It doesn't detract from their accomplishments, but it does remind us that they are just human.
In fact, it's sometimes our very weaknesses that God uses to manifest strength, healing, and forgiveness. A television personality like Tom Brokaw or Barbara Walters is all the more remarkable when we notice traces of their childhood speech defect in the way they say certain words. A young Glenn Cunningham was told after polio that he would never walk again, but went on to run the four-minute mile. A crossdressing Christian can share Christ's message with other crossdressers, often much more effectively than someone who never dealt with this issue. God can help us find purpose to our afflictions, whatever they are.
For me, the end to the guilt, fear, and shame I felt daily over crossdressing came the day I, a middle-aged pastor, offered my crossdressing up to God, to do with, as He saw fit. I remember telling Him he could take it away, or use it in any way he wanted. After I prayed, I felt a sense of relief. But it was in the weeks that followed that I received the real answer. First, I began to learn about the serious spiritual problems that plague the transgendered community--things like addiction, prostitution, and suicide. Next, I began to learn about these problems in detail. A radio ad told me that a suicide hotline needed volunteers. I received a flyer to study about alcoholism and drug addiction at a local university. And in that program I learned that prostitution is itself an addiction.
When I came out to my pastor at the time and told him I was transgendered, he kicked me out of his church. I knew then that the time was right to begin work with the transgendered community. I held the first service the next Sunday! That was the beginning of
The New American Christian Church. You can click on that colored text; it's a link to more information about the church, which is now in its fifth year.
We have seen people's lives turned from fear and shame and guilt. We have members recovering from alcoholism, prostitution, and suicidality. People have come to new faith here.
I now know that God created me this way for a purpose, and that purpose is to His greater glory.
And when I put on a pretty dress to wear to church, there's a reason for it far more important than my own satisfaction. And that makes the satisfaction so very much deeper!
I'll get off my soapbox now.
Feel free to email me at
RikkiOfLA@aol.com
The link I gave you to a Christian board may help you as it's the most common thing talked about there. 
