Must a person be baptized again in the case where the person who has long ago been baptized later gets converted to another religion, but eventually realizes the mistake and again gets back to Christianity?
Let’s look at a few scriptures before we answer your good question. In Matthew 28:18-20 the Lord Jesus said to His disciples, “All authority has been given to Me in heaven and on earth. Go therefore and MAKE DISCIPLES of all the nations, BAPTIZING them in the name of the Father and of the Son and of the Holy Spirit, TEACHING them to observe all things that I have commanded you” (NKJV). This commission tells us exactly what BAPTISM IS; it is “the initiatory rite of Christianity by which one officially becomes a disciple of Christ.” It does NOT save the person’s soul, for only “faith in the Lord Jesus Christ as one’s personal Savior” results in salvation, as we see in scriptures such as Acts 16:31, “Believe on the Lord Jesus Christ, and you will be saved.” The Apostle Paul made it perfectly clear in 1st Corinthians 1:17 that baptism has nothing to with the good news of salvation, for it reads: “For Christ did not send me to baptize, but to preach the gospel.” We conclude then that the words of our Lord have nothing to do with salvation; rather they speak exclusively of DISCIPLESHIP.
What exactly is a disciple? The word disciple means “a follower” and “a learner.” A disciple then is a person who “follows someone” and “learns from the person they are following.” The Lord said there are TWO things involved in one being a disciple; BAPTISM and TEACHING. BAPTISM comes first for in baptism the person is coming under the authority of the Lord Jesus Christ. We see this illustrated in 1st Corinthians 10:1-2, “For I would not have you ignorant, brethren, that all our fathers were under the cloud, and all passed through the sea; and all were BAPTIZED UNTO MOSE in the cloud and in the sea” (DARBY). Paul is no doubt referring to the time when all of the Israelites passed through the Red Sea. We know that Moses was LEADING THEM and thus when it says “all were baptized unto Moses” they were “under the authority of Moses and acknowledging him as their leader and guide.” I believe this is exactly what happens when a person is “baptized” into the Christian faith; they “own the authority of Jesus Christ and acknowledge Him as their Lord and Teacher.” They are, in essence, saying “I’m going to follow the Lord Jesus Christ and obey His teachings.” That’s why TEACHING is also mentioned in relation to being a disciple, for a disciple will continue to be taught “to observe all things that Christ commanded them.” At this point I would add that only one who has been SAVED can truly, from their heart, follow the Lord Jesus Christ. Jesus spoke of this in John 8:31, “If you abide in My word, you are My DISCIPLES INDEED.” When Jesus spoke these words there were many “disciples” who were not saved, so they were NOT “disciples indeed.” We read of them in John 6:60-66 and I would especially draw your attention to verse 66, “From that time MANY OF HIS DISICPLES WENT BACK and WALKED WITH HIM NO MORE.”
Now we prepared to try to answer your question. It appears the person you referred to is NOT like the ones just mentioned (who walked away from the Lord Jesus and never returned), for he “realized his mistake and returned to Christianity.” For a time he was not following Christ, thus his discipleship had “broken down” (we could refer to that as a “backslidden disciple”). Now that he has been restored to the Lord he can once again follow Christ. His discipleship is thus resumed. I see no scripture which would call for him being “baptized again”; in fact, there is a scripture which teaches the opposite. I’m speaking of Ephesians 4:5 where Paul taught that there is “one Lord, one faith, ONE BAPTISM.” There is “one Lord” (The Lord Jesus Who we follow); there is “one faith” (the Lord’s TEACHINGS that we observe); and “one baptism” (the rite which officially makes us a disciple in Christ’s kingdom). (298.5) (DO)