That is a question that can often be quite telling. Judging from certain comments on various blog posts, I have heard several folks chime in in what sounds to me to be fear, that we may NOT appeal to private (or personal) judgment when we ask people to evaluate the claims of the Lutheran Symbols against the touchstone of the Sacred Scripture.
Why not? Are people afraid of what will be discovered if they read the Scriptures themselves with a prayer for the Holy Spirit to help them understand them aright and then diligently compare them to the Lutheran Symbols?
I will be honest: I think certain Christians communions DO fear that. For they know perfectly well that they hold to practices and doctrine which CANNOT be demonstrated from the Sacred Scriptures - not even by inference. Was it not at Augsburg that a Roman apologist confessed that he could not refute the Lutheran position on the basis of the Scripture alone and an irate Roman layman said: "Am I given to understand that the Lutherans sit within the Scriptures and we without?"
A Lutheran does not fear the question: "Where is this written?" Rather, a Lutheran trains up his children to ask it ever. Not that our Church tosses that which is harmonious with the Scriptures and drawn from inference from them, even while not explicit in them (we DO baptize children, after all), but we hold that the dogma of the Church, her saving doctrine, is to be drawn explicitly and clearly from the Divine Scriptures and that what cannot be so drawn, or shown to be harmonious with them, cannot be set forth before the people of God as that to which they must submit on the grounds of the Church's authority alone. We flat out deny that the Church HAS such authority. She is indeed "the pillar and ground of the truth," but she is such as she speaks her Shepherd's life-giving words after Him, and not as license to dream up notions of her own.
So, yes, as a Lutheran I'd say to anyone: Here is the Bible, please take it and read it. Begin with the NT. Pray for God's enlightenment as you read. Trust that He will grant it. Seek to practice what you read and your understanding will grow. And compare what you read here to what our Church confesses in the Augsburg Confession or in the Small Catechism. We'd love to have you as a Lutheran, but only if you have been convinced that our teaching accords fully with that written in the Sacred Scriptures under inspiration of the Holy Spirit.
P.S. If you come and live with us for a while, you can see how we seek to live out this faith, and you'll no doubt notice that we are very weak in our lives even when we are strong in our doctrine. Such we find to be the case of fallen human beings who are being healing by God's mercy and grace. We are but poor sinners, and we literally live from the saving mercy of our God in Christ Jesus. Thus we rejoice that "all the law and the prophets bear witness that everyone who believes in Him receives forgiveness of sins in His name." Everyone. He means that. Glory to God in the highest!