Because Lutheranism is real world. It is not just an abstract idea.
THE REAL WORLD OF HUMAN SUFFERING
Very few people care about getting "ideas" right. Most people do not tend to live in their own heads. Instead, they experience the pain of real life. Marriages end in divorce. Loved ones die. Finances crumble. They lose their jobs. Disaster strikes.
All of this is the result of sin. This world is unpredictable. We have no control, yet folks want something that will give them some form of assurance. They tend to turn to religion, among other things.
But most of the time religion is not "real world." People who try different kinds of religion know that deep inside they are not "good." They know they try hard to be good, but deep down they know they keep failing.
It doesn't matter even if they turn to a kind of Christianity. In fact, I have had friends leave Christianity because they said they knew they were not "good enough." Certainly they were hearing a perverted form of the gospel to think that. The Gospel is supposed to be Good News. But they were not hearing "Yes and Amen." They were hearing "yes, but."
When you compare every religion except Lutheranism, no matter the nuanced differences, you will find that at the end of the day they all amount to this "yes, but." "Saved by grace after all we can do." "Your good deeds must outweigh your bad." "Yes you were saved but now what are you doing for God?" "Yes you know you are saved if you are repenting enough and bearing enough fruit." Etc.
Sooner or later folks in those kinds of religions and even kinds of Christianity will either experience self-righteousness or despair. Pride or burnout. They will either be legalists or give up altogether.
They must need something REAL.
THE REALITY OF OURSELVES
In truth, we all know that no matter how hard we try to be "good," that we are not. We may help the old lady across the street, but soon after our hearts try and pat us on the back and say "oh what a good boy/girl you are for doing that." We reason that we at least did not have sex with some person, even though we lusted after them. We reason that yes maybe we stole, but it was only ice cream. It is not like it was a sportscar. Yes, we may hate that person, but at least we did not kill them. Yes, maybe he killed six million, but he saw them to be merely vermin. Etc.
The sinful mind is professional with excuses.
And many Christians are walking Pharisees.
In reality, even after we become Christians, deep down we know that we are at the same time saved and yet still sinful.
We know all the so-called "free will" in the world is only self-motivating and selfish.
We know we need constant assurance of forgiveness.
CHRIST COMES CONTINUALLY TO ASSURE US
For those who are aware of their sinfulness, of their wretchedness, of the selfishness that their false "free will" always leads to--they know they constantly need Jesus. They know they only need Jesus.
They are not interested in an ecstatic "experience." They are not interested in "seeking God's secret will for my career path" or for "whom I should marry" or for seeking the (yet another!) "worship experience."
No.
In fact, they do not come to church to "give." Why?
Because they know they are only beggars.
WE ARE ALL BEGGARS
Beggars have nothing to give. They only kneel with their mouths open or their hands out.
And they respond in thankfulness to the One Who served them.
A beggar is in constant need.
And a beggar is taken care of by the One Who gives His Word, His Body, His Blood.
To receive forgiveness, and to eat and to drink for the forgiveness of sins, life, and salvation.
So why am I a Lutheran?
Because we are all beggars.
This is most certainly true.
