The only reason for 'not being 100% sure I am of the Elect', is the evidence of my works, and my sometimes rebellion against what I know to be right, and rebellion's accompanying reminder that I can be fooling myself. I have no doubt of the power of Christ's sacrifice.
Or you could believe Jesus in Mark 16:16 that says that those who believe and are baptized will be saved. Mark 16:16 is what Jesus commanded His disciples to preach just before He left them, and should rid the naval gazing caused by wondering if one was selected to election - which is caused by preferring Calvin''s fatalistic theology, which came 1500 years after Jesus, over Jesus's words. Even if Calvinist predestination is true (which I don't see), it cannot affect the truth in Mark 16:16!
Sadly, there are many sensitive individuals that espouse Calvinism who post on this forum that they are at their wits end as that they want to be saved but are unsure if God elected them - they should have been taught Mark 16:16.
When you really get to Calvinists with scriptural argumentation they will sometimes throw out "you follow a different Jesus" without an explanation! Just an unintelligible smoke screen. The other smokescreen, is claiming you are trying to be saved by works. Their problem is with Peter who pleads with sinners and promises that those who repent and are baptized will receive remission of sins and the gift of the Holy Spirit (effectively salvation) in Acts 2:38-39 - showing man that he has his part in being saved - which Mark 16:16 also presents if one reads it without preconceptions. It is not too late to take up Peter's promise in Acts 2:38-39 - which lines up nicely with Mark 16:16 and Romans 10:9-10. It is after all the Gospel (good news)! God is not the one blocking men from receiving salvation (per 1 Timothy 2:4) - it is satan (2 Corithians 4:4).
My experience is that Calvinists give a number of scriptures (i.e. their proof texts like 1 Peter 1:2) that can be interpretted multiple ways concerning predestination and will not discuss an interpretation that does not support Calvinism. On the other hand, they reject the plainest of scriptures like 1 Timothy 2:4 that says that God "desires all men to be saved" which refutes Calvinism. 1 Timothy 2:1 says Timothy (and arguably us) are to pray for the same "all men" in 1 Timothy 2:4 and 1 Timothy 2:6. Although God desires all to be saved, it is not automatic as receiving anything from God requires faith. When Jesus walked the earth, he told men multiple times that their faith saved them. Faith comes by hearing the word of God (Romans 10:17) - so per scripture it is attainable to all who are careful in what they listen to - make sure you are listening intently to the word of God (directly from the Bible or from a preacher).
Recently Mark Q, has stated that he will not respond to my posts as he infers I am conducting spiritual warfare against him. He says I use a war hammer - ha, ha. Paul describes the word of God as a two edged sword - not a war hammer. Paul instructs us to conduct spiritual warfare against imaginations, thoughts, and high things that oppose truth:
2 Corinthians 10:5 Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;
Concerning arguments against Calvinism: I frequently quote the Bible and John Calvin, but Mark Q. states he has never read Calvin - even though Mark Q. has posted in support of Calvinism thousands of times on this forum. Its nothing personal: Mark Q. is a nice (acting fair minded and respectible) Calvinist, but is unprepared to debate as he states he never studied what Calvin said and tends to present philosophic arguments (like what he terms "First Cause") that are not in scripture. Calvin's "Institutes of the Christian Religion" were translated long ago and are roughly 1500 pages in length (so plenty of material)! I prefer to discuss "Calvinism" strictly from the Bible and Calvin's own words - although to a lesser degree I will listen to modern leading Calvinists (like Spurgeon, MacArthur, Piper, Pink, Keller, James White, etc). Having Mark Q. frequently say "I told you ...." does not register with me - I need something authoritive - again nothing personal!