Well, that's a lie.
I think that, because the Bible teaches that.
Lie #2.
Agreed. We obey by believing the gospel. That's all the "if" required. To add anything else implies Jesus did not pay our debt in full.
That wasn't just a "special time". You are once again adding to God's word with your opinion. Show me the scriptures that Jesus only sealed a certain group of people for eternal security.
Then salvation isn't a gift, grace isn't unmerited, and our sin debt was not paid in full. If any of that were true, Jesus would have to come back and shed more blood for the remission of any sins not paid for by His first atonement.
That's your tired old "pay to play" salvation by works, raising it's wicked, evil, demonic head.
Jesus was asked specifically what are the works God requires of us. That's why I always ask you for specifics, but you only deal in generalizations.
Here is the only "condition" - the only "works" required:
"Then they said to Him, “What shall we do, that we may work the works of God?” Jesus answered and said to them, “This is the work of God, that you believe in Him whom He sent.” (John 6:28-29)
Notice Jesus said "work" not "works".
You'd better realize something soon. God will not save anybody who is trying to save themselves by their works. If you believe any form of behavior or performance in life has any part in your salvation, God cannot and will not save you. You believe Jesus is necessary, but not enough.
You're essentially claiming that the sin debt was not fully paid by Christ. That by our continued obedience, the sin debt is being paid. Because, according to you, if we don't continue to work, we will lose our salvation. That places the onus on us and not on Jesus.
Cue you giving lip-service to Christ's sacrifice while bragging of your own salvific accomplishments.