Now, now! Certainly there is truth in your accusation. Infant baptism may in fact lead to this sort of complacency. Personally, I have railed against this kind of thinking in my own Lutheran church. However, I also have a number of friends who come from adult baptism traditions who assure me that there are many teens in their churches who are baptized simply because everyone (parents, grandparents, pastors, teachers) expects them to do it, not because they are expressing a real faith of their own. I have also known many Christians, baptized as adults, who are content with "I-trust-Jesus-as-my-personal-Lord-and-Savior-and-I'm-going-to-heaven" -- but they never grow into the mature faith Paul and the rest of the New Testament calls us to.
Would you deny that there are many Christians who have been baptized as infants, who have then been nurtured in faith and grown into a vibrant relationship with God in Jesus Christ? I know quite a few such Christians in Lutheran and other infant-baptizing churches, as well as those who come from adult-baptizing churches.
The trouble in both our traditions, it seems to me, is that authentic discipleship is too rarely modeled and that baptism can too easily become a rubber-stamp exercise no matter what age it's done.
While there may be those who are being baptized as adults who do not understand the Gospel (1Cor.15:3-5), that is the fault of the Baptizer.
There are those who come to faith in Christ after being baptized as an infant, however, there are many more who never do, thinking that the baptism put them into the Church and they are thereby saved.
It is not scriptural, but traditional, a hold over from Roman Catholism.
Even so come Lord Jesus