Thayer's Greek Lexicon

 1. immersion, submersion
  1) of calamities and afflictions with which one is quite overwhelmed
  2) of John's baptism, that purification rite by which men on
confessing their sins were bound to spiritual reformation,
obtained the pardon of their past sins and became qualified
for the benefits of the Messiah's kingdom soon to be set up.
This was valid Christian baptism, as this was the only baptism
the apostles received and it is not recorded anywhere that
they were ever rebaptised after Pentecost.
  3) of Christian baptism; a rite of immersion in water as
commanded by Christ, by which one after confessing his sins
and professing his faith in Christ, having been born again by
the Holy Spirit unto a new life, identifies publicly with the
fellowship of Christ and the church.

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In Rom. 6:3 Paul states we are "baptised unto death" meaning that we
are not only dead to our former ways, but they are buried. To return
to them is as unthinkable for a Christian as for one to dig up a dead
corpse! In Moslem countries a new believer has little trouble with
Moslems until he is publicly baptised. It is then, that the Moslems'
know he means business, and then the persecution starts. See also
discussion of baptism under No. G0907.