Kim,
I pray you are sincere in seeking answers as was the Ethiopian eunuch in Acts 8:26-40. As Bob succinctly shared very good answers, I have identified seven statements or ideas in your post that I would like to share my thoughts and God’s Word on the matter. My brother was a practicing homosexual and also my business partner until his Aids Related Complex sent him into a comma and ultimately ended his life. I miss him terribly but have found complete truth and understanding in the living and active Word of God. I am sorry, but I can’t be as brief as Bob, but his answers were spot on, thank you brother.

#1 The Bible seems to support or condone sinful actions like multiple wives.
There are many actions of O.t. people that are reported prior to the giving of the Commandments. This, however, is not “supporting” such sinful actions. According to Rm.5:12-14, the consequence of sin is death, we all die, therefore all sin. Every O.T. believer (saint) is also a sinner, and the Bible honestly and clearly reports this. Abraham and Hagar’s union was Sarah’s desperate plan, not God’s. Israel’s desire to have a worldly king, with all their wives and political and social conflicts, was not God’s idea. The Bible reports these sinful actions as well as their consequences: Divided homes, jealousy, adultery, idolatry, destroyed kingdoms.

#2 The Church should not pray for homosexuals to successfully struggle against their desires.
The church prays for every sinner to successfully struggle against their temptations to sin: youth to remain firm in God’s Word and refrain, that is to struggle against, pre-marital sex; For husbands to remain faithful, that is to struggle against their sinful natures, and find fulfillment only in their wife; For those with addictive or abusive behaviors to be struggled against constantly. All have sinned. We all are to struggle against temptation in general and those that are particular to ourselves. To pray for Christians to have success in resisting daily temptations is a very good and loving prayer. The opposite is to encourage people to yield to sin and become a slave all over again. (Rm6:15-18; Jn8:34; Eph4:22; Ps50:15)

#3 Homosexuality a choice?
Luther did not teach that we are born with a free will, rather with a bondage of our wills to sin. In other words, sin comes natural to us, righteousness does not, it is a gift of faith. The bully finds it natural to pick on others, the child who lies to keep from getting punished does so naturally, this is our sin nature. It has fallen far short of God’s intended glory for us in the beginning. So, homosexual desires are no more a choice than my sinful heterosexual desires, but when those desires are contrary to the will of God as revealed in Scripture, then they spring from our sinful nature. (Ps51:5; Rm5:12; Eccl7:20; Ps14:3; 1Jn1:8; Jms1:14-15; Mt15:19) Please note that this applies to all sin: Religious, spiritual, communal, social, heterosexual and homosexual etc. But when discussing homosexuality in particular read these passages of God’s Word (Rm1:24-27; 1Cor6:9-10). The Law was given to show us our sin, that we might repent (turn from) those sins on a daily basis (Titus 2:11-12). Jesus died for heterosexual and homosexual sins. We sinners are justified/forgiven by His death and resurrection, but this atonement does not justify (make right) our sin. Therefore, in baptism and constant living in the Word of God, we are reborn and strengthened to resist our sinful nature (Gen39:9; 1Cor6:18; Eph5:3-4; 1Cor6:19-20;1Thess4:3; Col2:6; Titus 2:14; Gal2:20; 1Pt2:24). This is a daily struggle of confessing our sins, asking forgiveness, and our victory is assured only in Christ. By grace, NOT our works (of choice), we are enabled to thankfully do His will and not our own. (1Pt2:9; Acts 3:19; Ps32:5; Jn8:11; Mt3:8.)

#4 Martin Luther railed against Archaic teachings.
Martin Luther did not rail against the Roman Church for having archaic teachings, but for having man-made teachings in conflict with God’s Word. There are many modern “positions and teachings” today that are ungodly and deserve Luther’s “railings,” but I suggest that the good Doctor would rather both Rome and modern liberalism would reform to a Church that professes and teaches all of the Bible’s doctrine purely and administers the sacraments according to Christ’s institution, but alas, they would not. (Jn15:5; Jn8:31-32; Acts 2:42)

#5 Demonizing homosexuality is equal to the past demonizing of interracial marriages.
This comparison of a Biblical doctrine on homosexuality or any sexual immorality with that of “demonizing’ interracial marriage, is an emotional argument disconnected from a Biblical discussion. Sin is lawlessness, rebelling or acting contrary to God’s Law and will. “I am a sinner,” that does not demonize me, it informs and warns me of the truth so I can cast aside faulty notions of self-righteousness and receive the grace of God in Christ. The non-Biblical errors of human beings, does not nullify the eternal Word of God. Please discuss these volatile issues honestly and Biblically.

#6 “Shame on us for not sticking with the 10 Com, Love one another, and Belief in Him.”
You seek to admonish a church body for being, as shown in the above Bible texts and explanations, absolutely correct and faithful. That is not to say we are a denomination without need of admonishment, but our Confessions are Christ and Word centered, while others are becoming worldly and full of empty philosophy. We certainly stick to the 10 Commandments, which is why we point out and confess our sins, including miss-use of our sexuality. Take a fresh look at your Catechism. “Love one another” is simply the second table of the Law from those same 10 Commandments, and for our discussion means that we are not to cause harm or cruelty to an unbeliever, but tell them the truth in love. Belief in Jesus includes trusting His Word, every letter of it, even if it doesn’t jibe with the wisdom of this fallen world. This is the true unity Paul speaks of. (1Jn4:1; 2Tim4:3; Jn8:31-32; 1Cor1:10)

#7 Why should we venture beyond the 10 Commandments and belief in Him?
I would be fine with that…right up to the point someone denies that misuse of our sexuality does not violate the 6th Commandment, or that “belief in Him” means we can love our neighbor without pointing to sin and calling for repentance as John did, as did Jesus, and Peter, etc., etc. If your friend or loved one is dead in sin, love demands that you warn them of the danger, and offer them life through the forgiveness of those sins (Jn:3:16). God gave the entire Bible because He knew false prophets and teachers would twist those clear Words, and the rest of Scripture combats this by interpreting itself, and thus leaving no excuse for those who misuse it for evil, when it was intended to be for our good. I know where you are at because I have been there. Don’t make up any pseudo-science, nor embrace the emotional rationalism of the day, but just love your homosexual friend, neighbor, son or daughter without yielding God’s entire Word of Truth an any way. They need to hear God's truth from your compassionate heart and lips. There will be a day when the scales will fall from our eyes and you will be glad you did. (Jn6:63; Rm1:16; 2Pt3:15-16; Jn10:35; Mk8:38; 2Tim3:16-17; 2Pt1:21; Acts 17:11)