Baptism, say the proponents of infant baptism, is merely a sign that the child is part of the larger community of God's people, the church in general. However, how is baptism shown in the pages of scripture? It is linked inextricably to salvation. See how each of the following baptisms is linked to those who have been converted, not to those who may or may not be converted years later.
Romans 6:4 We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
Acts 22:16 And now why do you wait? Rise and be baptized and wash away your sins, calling on his name.’
Acts 18:8 Crispus, the ruler of the synagogue, believed in the Lord, together with his entire household. And many of the Corinthians hearing Paul believed and were baptized.
Acts 8:13 Even Simon himself believed, and after being baptized he continued with Philip. And seeing signs and great miracles performed, he was amazed.
Acts 2:41 So those who received his word were baptized, and there were added that day about three thousand souls.
Acts 2:38 And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.
Mark 16:16 Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.
1 Peter 3:21a Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ
What more needs to be said? There is a bond between baptism and salvation where, as shown clearly above, those who are converted receive baptism. Those who say infant baptism is appropriate minimize the importance of baptism by saying those who are not yet converted may participate. The sign and seal of God's covenant of grace is much too glorious a thing to say it merely signifies entrance into the broader, not so much saved, community of the "church". No. It is much more important and sacred than that.