How should Christian businesses serve LGBT customers? I've had my share of "abuse" from both sides of the fence. Far-left and far-right. Far-left being more crude and ignorant of bible passages than far-right (far-right simply follow political trends and don't understand full-bible story).
1. The same as each individual customer, with basic kindness and respect. Ask no questions about 'medical history.'
2. Serve only 'one name' per order. Catering orders never ask for 'type' of marriage or ceremony.
3. If questions about your faith are asked, simply explain bible verses which explain faith. Do not attempt to just generally say 'I believe in one-man-and-one-woman marriages, and that's final,'. As this is not the true reflection of Christian faith. (Bible speaks about polygyny, polyamoury (brotherly and sisterly love), and the reality that Jesus loved Lazarus....go ahead, read-it, Jesus himself had platonic brotherly love)
4. Don't "idolize" sexual impurity and perversions. That is the ditch of hyper-grace. You are NOT a Christ follower if you do not believe in correcting men in their sin and perversion (including men in one-man-one-woman marriages caught in infidelity...... even John the Baptist corrected a divorced and remarried man). Putting a color-full flag on your business door, facebook page, bumper stickers, etc etc. proves nothing in regards to faith, as idolatry and faith are not mixable. (Read about how Jesus spoke about Capernea.......they were worse than Sodom and Gomorrah)
5. With the same attitude that all customers should show the business respect, equally. No matter what. If they are angry and crude in your store, then they should leave or call emergency number to have them removed and jailed. Any man or woman who is caught putting "feces" or dancing in rated-x costumes in a family based and run business does not deserve to be treated with kind-service, they deserve justice.
6. If you are being "persecuted" by such customers, it is up to you on how you wish to handle the situation. You may a. love the enemy......invite them to dinner b. pray for the enemy c. flee persecution. (Jesus said to do these things)......dependent on the situation. If you DO invite them to dinner, you may find out that they had a bad-history in the beginning of their life which led them to such a lifestyle. Abuse, neglect, homelessness etc. Be merciful......they can and do repent of sin if they are given the knowledge of what to do. People don't go to "hell" because they practice their sin lifestyle, they go to "hell" because they don't accept that Jesus paid the price for their sin lifestyle and choose to follow him on this earth.
7. Do not give into the "liberal clutter Christianity" which says the patriarchy Christians, conservative Christians, zionist Christians etc. are crude to LGBT people, because they believe that "lust" can be cornered and stopped by more bible study, service towards others and prayer. Bible meditation is MEDICATION for the soul. The way to bondage is to cater to the world-system rather than attention to "the word." Bible study and reflection HELPS people make better choices in life, so it does help LGBT people overcome many issues in their life.
So in summary, when you are "over the rainbow" and over the reality that sexuality is not a reflection of Truth......unless done according to God's laws and purposes.....then Follow the Yellow Brick Road : https://www.youtube.com/watch?v=aYvs9cB3qVk
Furthermore a person simply CANNOT call themselves Christian or a Christian CHURCH if they are in favor of "Sodom and Gomorrah" lifestyles. Jesus himself referenced Sodom and Gomorrah more than one time, and each time he referenced it in negative frame of mind, so that indicates that he is OPPOSED to such ways of going through this life. (Mat 10:15, Matt 11:23, Matt 11:24, Mar 6:11, Luk 10:12, Luk 17:29). A person can support platonic brotherly love.....but they cannot support "Sodmon and Gomorrah" sexuality, practice and lifestyle.