Miracles and signs
The Bible often speaks of signs and miracles as things that convinced people of the Lord's leading. "Signs" convince people to believe intellectually, and "miracles" convince people to believe emotionally. For instance, it was a "sign" for the shepherds that they would find the newborn Jesus wrapped in swaddling clothes, lying in a manger. This was not something that defied explanation; there is nothing impossible about a baby being laid in a manger. On the other hand miracles such as the Nile turning into blood, the Red Sea parting or water being made wine were apparently impossible, striking awe and fear in the hearts of observers and thus compelling the emotions. Both signs and miracles, however, are external events that could only force people into compliance out of fear and awe, which is an external form of worship that has little to do with eternal life. The Lord used them in Biblical times because the people of that time were external in nature, and the Lord had to force them into forms of worship to preserve spiritual ideas and to allow for the Bible to be written. Through His advent and His teachings He opened the possibility that we could understand His spiritual meanings, which would allow us to believe and live internally, not just externally.
The New Jerusalem and its Heavenly Teachings #173
173. Regeneration
Anyone who does not begin to live a spiritual life-that is, who is not born anew by means of the Lord-cannot come into heaven. This is what the Lord tells us in John: "Truly, truly I say to you, unless you are born again you cannot see the kingdom of God" (John 3:3).