Without yet conceding that he Marriage Act in Australia will change, invitations to same sex-weddings are already out there. They will only become more common, though certainly not proportional to the debate that is now raging. And so it is certainly worth thinking through the predicament before you find yourself in it: can a Christian accept an invitation to a same sex wedding?

While the definition of marriage is under debate, so too may be the definition of a "wedding". For the purpose of this discussion, I am presuming that if you have been invited to a "wedding", then it can be defined as the mutual consent and solemn vow between two people to love one another exclusively for life made in the presence of witnesses. As such, it is a public event or, at least, as public as the circle of family and friends invited to witness the occasion.

From a Christian perspective, we understand that it is important to make marriage promises in the context of community. As much as some might like to think "what I do in my relationships doesn't affect others", it does. This is right and good. Marriage is a social institution. Marriage promises create a family that is the basic building block of society. The importance of family in the context of society is clearly seen in two of the six commands in the second table of the Ten Commandments — the commands to honour your parents and not to commit adultery.

The emphasis on marriage and parenting is also significant in the household codes of Ephesians 5:21-­6:9, Colossians 3:18-4:1 and 1 Peter 2:13-3:7. By inviting you to their wedding, a couple, maybe unwittingly, are making themselves accountable to you, their community, for their promises to love one another. They are looking to you for your blessing and support in their endeavour.

So should you go?

It is important to differentiate between a same-sex "Christian" wedding and a same-sex wedding that makes no reference to the God and Father of our Lord Jesus Christ. 1 Corinthians 5 makes very important distinctions between how we are to respond to sexual immorality, depending on whether it is committed by someone "in the world" or by someone who calls themselves a brother or a sister.

For those who call themselves brothers or sisters, the response required is loving correction and discipline. Their immorality is not to be celebrated (1 Cor. 5:2). Paul's encouragement is "with such a man do not even eat". It is very hard to see how one could sit down at the wedding banquet of one who is supposedly a brother or sister and yet is solemnising a same-sex relationship with "marriage" vows.

In the wedding ceremony itself, if there is prayer for the couple to the Father in the name of the Son, will you say "Amen"? Will you ask God to bless that which He has clearly said He does not? Such a prospect is terrifying.

What if the Bible is read? It is one thing to unwittingly find yourself in a Sunday service where the Bible is flagrantly misconstrued — you may choose to walk out or politely endure the event but then not return to that church again. But will you knowingly walk into such a situation? How will you feel sitting through that service without making a stand? The prophets and Jesus Himself reserved their most severe rebukes for the unfaithfulness of Israel's leaders rather than the idolatry of the world.

What about those friends you have who are "in the world" and invite you to their same-sex wedding? In 1 Corinthians 5:9-12, Paul qualifies his command not to associate with sexually immoral people by saying "not at all meaning the people of this world ... in that case you would have to leave this world. ... What business is it of mine to judge those outside the church?"

At first glance, this might seem to leave us free to attend such a same-sex wedding. However, while it gives us freedom to associate with such people as Jesus did in the attempt to lovingly call them to repentance and faith, it is quite another thing to attend their wedding ceremony.

Paul refers to a similar distinction in 1 Corinthians 8-10. It is OK to purchase at the market the meat sacrificed to idols and then to eat it: for "we know that an idol is nothing at all in the world and that there is no God but one" (8:4). But it is quite another thing to "participate in the altar" or the "table of demons" by going to the temple and eating the sacrifice offered to the idol (10:18-21).

The Corinthian Christians may have protested "but I don't believe an idol is anything. I am just going through the motions because it is part of being engaged in Roman society". But Paul would say "Are we trying to arouse the Lord's jealousy? Are we stronger than He?" (10:22). Daniel endured the lions' den and his companions the flames rather than fall in line with public idolatry.

Finally there are some other practical implications for a Christian to consider in accepting an invitation to a same-sex wedding. If you did accept, thinking you are just a passive observer and not actively supporting the wedding, here are some parts of the service where you may well find yourself "on the spot":

• If the celebrant were to ask "Does anyone have any reason why this wedding should not take place?", what will you do in that moment? Do you remain silent, even though you do have sound biblical reason to speak up ... just to keep the peace? Or do you speak up and radically disrupt the proceedings?
   
• Or when the couple are pronounced "husband and husband" or "wife and wife" or, more likely, pronounced "married", and everybody claps as the groom kisses the groom, will you join in and celebrate with a clap and a cheer at that moment? Attendance with the intention of raining on the party is not really in the spirit of an invitation acceptance.
   
• Photos in the context of social media will bring you a great dilemma. Photos posted of you with the couple can be posted with any subtext like on the groom's Facebook page — "with my friends supporting our life together". It drags you into a false, or at best, confusing public witness.

So, how then might you lovingly handle an invitation to a same sex wedding?

Show genuine thankfulness for the invitation and deep appreciation of the fact that they have included you among their close community. Your refusal will bring pain to all parties. Acknowledge this as it shows how much you care about the couple involved and your relationship with them.

Give clear refusal with the request that your different view on this issue be tolerated or even respected. It is easy to pretend that you couldn't make it because you had something else on but this can just be insulting. As Christians our "yes" is to be yes and our "no" no.

Continue to work hard at prayerful and loving engagement. Declining the invitation will test your relationship. Do not be the one to turn away from the relationship. Do what you can to show that you care about them in as many other ways and remember, our hope is not to see them come to heterosexuality, but to Jesus the friend of sinners.