Q. I fear that the sins I committed before trusting in Christ were unpardonable, and thus I doubt my salvation. Could I have committed the unpardonable sin and yet have also sought to trust in Jesus?
John 6:37 clearly states that if one comes to Jesus, He will certainly not cast him out. And, if we look at the first part of this verse, we must also conclude that the one who comes to Jesus is one whom the Father has given our Lord.
When we look at Mark chapters 3 and 4 we see that Jesus spoke in parables so that those who committed the unpardonable sin would not understand the gospel, and thus would not trust in Jesus:
28 “Truly I say to you, all sins shall be forgiven the sons of men, and whatever blasphemies they utter; 29 but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin “-- 30 because they were saying, “He has an unclean spirit” (Mark. 3:28-30, NAU).
11 And He was saying to them, “To you has been given the mystery of the kingdom of God, but those who are outside get everything in parables, 12 so that WHILE SEEING, THEY MAY SEE AND NOT PERCEIVE, AND WHILE HEARING, THEY MAY HEAR AND NOT UNDERSTAND, OTHERWISE THEY MIGHT RETURN AND BE FORGIVEN” (Mark 4:11-12).
Obviously, you have come to understand the gospel, and to have trusted in Jesus, so you must not have committed the unpardonable sin.
Further, in the Gospels the unpardonable sin is defined as attributing the work of the Holy Spirit in Jesus to the devil. All other horrible sins, Jesus said, are pardonable, including blasphemy:
28 “Truly I say to you, all sins shall be forgiven the sons of men, and whatever blasphemies they utter; 29 but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin “-- 30 because they were saying, “He has an unclean spirit” (Mark 3:28-30; see also Luke 12:10).
I think of Saul, who became the apostle Paul. He committed terrible sins against the church, and thus against Christ (see Acts 9:4), but Paul makes it clear that God saved him because of His grace and for His glory:
12 I thank Christ Jesus our Lord, who has strengthened me, because He considered me faithful, putting me into service,
13 even though I was formerly a blasphemer and a persecutor and a violent aggressor. Yet I was shown mercy because I acted ignorantly in unbelief; 14 and the grace of our Lord was more than abundant, with the faith and love which are found in Christ Jesus. 15 It is a trustworthy statement, deserving full acceptance, that Christ Jesus came into the world to save sinners, among whom I am foremost of all. 16 Yet for this reason I found mercy, so that in me as the foremost, Jesus Christ might demonstrate His perfect patience as an example for those who would believe in Him for eternal life. 17 Now to the King eternal, immortal, invisible, the only God, be honor and glory forever and ever. Amen (1 Timothy 1:12-17).
Your sins, committed before your salvation, serve to demonstrate the grace of God, which now should assure you of your security in Him:
For while we were still helpless, at the right time Christ died for the ungodly. 7 For one will hardly die for a righteous man; though perhaps for the good man someone would dare even to die. 8 But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. 9 Much more then, having now been justified by His blood, we shall be saved from the wrath of God through Him. 10 For if while we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life. 11 And not only this, but we also exult in God through our Lord Jesus Christ, through whom we have now received the reconciliation (Romans 5:6-11).
Remember that Satan is “the accuser of the brethren” (Revelation 12:10). So who do you think wants to undermine your faith and cause you to doubt the greatness of God’s work of salvation in you?