"But as many as received Him, to them He gave the right to become children of God, {even} to those who believe in His name," (John 1:12).
"For by grace you have been SAVED through FAITH, and that NOT OF YOURSELVES; it is the gift of God, not of works, lest anyone should boast" (Eph 2:8-9).
Although a person may have committed many sins, the chief sin of the unsaved is NOT BELIEVING ON CHRIST john 16:9). When a person gets that straightened out, the root of the problem is solved. The blood of Christ cleanses the heart the moment a person believes and confesses Him as Savior. Thus all the past sins are remitted or taken away by the powerful cleansing work of His blood (1John 1:7). "…We have redemption through his blood, the forgiveness of sins, according to the riches of his grace; (Eph 1:7).
At the close of his message on the day of Pentecost, Peter told the Jews, "…Then Peter said to them, "Repent, and let every one of you be baptized in the name of the Father Son and Holy Ghost for the remission of sins; and you shall receive the gift of the Holy Spirit." (Acts 2:38). Luke Records, "Then those who gladly received his word were baptized; (Acts 2:41).
Paul was baptized after his conversion (Acts 9:18). He later baptized the believers at Ephesus (Acts 19:1-6). Those at Cornelius" house were baptized after they had received the Holy Ghost (Acts 10:44-48). The Philippian jailer and all his household were baptized after they had believed on Jesus (Acts 16:31-33).
If you meet the conditions given in God's Word for salvation, you can know you are saved. God's Word says that you can know. That is what you must stand on - His Word - Not your feelings, emotions, church membership, high morals, or sincerity.