After reading through this thread, I have heard many objections that in years gone by I would have used myself many times over. Especially things such as the distinction between water baptism and the baptism of the Holy Spirit. Even now, not just I but most Lutherans would agree, that being baptised in water alone is simply as powerful in and of itself as a shower or bath. Rather it is the regeneration worked through the Holy Spirit that brings to us eternal life. And before anyone replies "not the Lutherans I know..." etc., here is what is actually written in the Book of Concord (Small Catechism on Holy Baptism)
To paraphrase my pastor, "Although God is omnipresent, we must seek Him where He has promised to be found." This is why the Lutheran view of baptism is not a work we carry out in obedience, but it is rather a work of God we surrender to in faith, that unites us with Christ in His death and resurrection life. It becomes the tangible and personal connection point for the believer, to the benefits of forgiveness and eternal life Christ secured upon the Cross. It is what changes the good news of Christ dying upon the Cross for the sins of the whole world, to Christ giving His life as a ransom for me personally.
The fact is that in all types of churches, there is a constant craving for the certainty of salvation. Not so much that we doubt that the death and resurrection of Jesus Christ is sufficient to forgive our sins, but that we often have nagging doubts that we are truly of those He died for. I remember in my years in the charismatic church, and the pentecostal church I attended, this certainty could be sought after in the decision I made, or whether I spoke in tongues etc.. Or in my time in the Reformed Baptist church, that evidence was sought in a progressively more holy life. But the common thing was that it was always something "in me" rather than outside of me. I know this would be denied in reformed circles due to the teaching of the Sovereignty of God in salvation etc., but the evidence that I am personally of the elect (which troubles many Calvinists), is usually to look for a sanctified and holy life for comfort.
The primary difference I have found in the Lutheran church is that all our comfort is outside of ourselves (extra nos). If we are plagued with doubt and unbelief etc., especially when coupled with the grossness of our own sinfulness at times, we have a clear and tangible place to look to for our own comfort. We can know that, regardless of how things may appear to us, in our baptism we already died with Christ, and continue to do so daily. Because His Word says so. We can know that we have the Holy Spirit, not because of any outward manifestation, but because His Word promised He would be given to us in our baptism.
As Lutherans we do not look at our baptism as a one off work that we carried out in obedience to God, but rather as I said earlier, it is a work that God does to us in uniting us to His Son, both in His death and life, and equips us with the gift of the Holy Spirit as a deposit that guarantees the life which is to come. This is our daily hope, and in our baptism we die daily to ourselves, and are raised again with Christ according to the promises of His Word.