Good honest answer, and the way you worded it, you seem to understand completely where you are at.
I am sorry I was snippy earlier with people. It is difficult to explain the influence Lutheranism has been on my life. I get defensive sometimes. Lutheranism has a great treasure and I don't want it to be hidden away, so you must forgive my zeal.
Sometimes Lutherans are accused of being antinomian, because we do not emphasize God's law the same way other Christians do. But I think we just understand God's law differently. We believe in doing good in the world, but not in a particularly religious way. We don't emphasize using the Law as a guide for Christian behavior in the same way as other churches do.
I am formerly Eastern Orthodox and I left the church because me and my partner are disabled, so we could not marry, and my priest told me I was excommunicated. I made my way to the Lutheran church through alot of prayer, and a little bit of study. It has been great because I have found Christians who are not legalistic, and understand what it is like to feel broken and powerless.
It might be hard to understand where we are coming from, if you are used to other Christian traditions. We Lutherans believe human beings are by nature powerless and helpless to please God, to love God and serve him as he deserves. It's not a matter of just not willing to do good, but unable to be good enough. So we needed God himself to step into our broken humanity and do what we could not do, to bridge the gap between God and us. As a result, we have an ethic of compassion, and we are willing to put aside moral scruples much of the time in the name of helping people, especially helping people to feel loved and accepted by God. Because that is exactly what God has done in Christ ,he has set aside the demands of the moral law because he loves us, and because Christ has fulfilled all righteousness for us. We look to things like sciences and humanities to help us guide us in our ethics, but our primary example is always Jesus.
The Lutheran understanding of the Gospel is an important thing in today's spiritually confused world. It has set me free from the dark side of religion, and that is why I am so particular about it.
So... I can understand where Bishop Brunne is coming from. I too want Muslims to feel safe and loved. If that means giving Muslims a space to worship in a way that they can understand, I do not see it as a heinous sin. I would prefer a cross to be there, but I don't see how its bad to be kind to strangers who may be very far away from home.
My discomfort with evangelicals worshipping at my church is because I know exactly how this sort of Christian religion works, and it very far from how I understand the Gospel now as a Christian. In fact I would say it has more in common with Islam than with my faith. Sure, it has Jesus, but its not usually the Jesus I know, the one that came for the least, the lost, and the last, and he gives them the Kingdom as a free gift. It is not an offer of salvation, it is a gift.
In comparison most evangelicals preach a message of moralism, if not legalism, just as the Orthodox do, not that different from the Muslim. The Muslim knows no better, but the christian claims to know Jesus. So, I am tempted to judge the Christian more harshly.