Now when the apostles which were at Jerusalem heard that Samaria had received the word of God, they sent unto them Peter and John:
Note 1 at Ac 8:14: This was the first time in the experience of the young New Testament church that anyone except a proper Jew had become a believer in Jesus. The Samaritans were Jews who had corrupted their bloodline and the true worship of God, and they were therefore rejected by strict Jews as not being Abraham's seed and heirs to the promises (see note 2 at Joh 4:4).
Because of this, the church at Jerusalem sent Peter and John to Samaria to check out what was happening there and see if they approved. Peter and John showed their approval by praying for the Samaritans that they would receive the Holy Ghost and even shared the Gospel with other Samaritans on their way back to Jerusalem (Ac 8:25).
Jesus had ministered to the Samaritans before (Joh 4:4-30 and 39-42) and had made it clear that He was the Savior of all (see note 2 at Mt 15:26 and note 1 at Joh 12:23). The believers came to accept this concerning the Samaritans, but the same wrong thinking cropped up again when it came to the conversion of a Roman centurion named Cornelius (Ac 10). This doctrinal issue of "Does one have to become a Jew to be saved?" caused a convening of a special council of the apostles and elders at Jerusalem to consider this issue (Ac 15:1-31). Three books of the New Testament (Romans, Galatians, and Hebrews) were written containing the major theme that salvation in Jesus comes through grace by faith alone.