Cross Defense: The Apologetic of Infant Baptism with Christians Opposed To It

Many non-sacramental Christians perceive us sacramental Christians as legalistic and weak in faith.  What is behind this and how should we make our defense?  Direction of theology; mingling of justification and sanctification; Law and Gospel distinguished; God gifting or humans acting in obedience?; Does the depravity of original sin allow decision to believe and be baptized without God’s grace in the means of grace?