Do you have 100% assurance that if you would die tonight that you would go to heaven?

You can!

BAD NEWS:
Your a Sinner in need for a Savior.
Romans 3:23 "All have sinned and fall short of the glory of God."
"Sinned" means to miss the mark. The mark is God's standard. Sometimes we like to judge our 'goodness' up against other people, but God is the standard.

"To fall short" means that it doesn't matter how many good things that a person does, he still falls short of God's holy standard.

Since we are sinners, the penalty for our sin is death.
Romans 6:23 "The wages of sin is death."
This death is eternal separation from God forever.

Man was and still is unable to do enough good works to make it to heaven, so God came to us.

GOOD NEWS:
Galatians 4:4 But when the fullness of the time came, God sent forth His Son, born of a woman,

Romans 5:8 God demonstrates His own love toward us, in that while we were still sinners, Christ died for us.  
God sent his Son, Jesus,  to save us from our sins and to die on the cross.

1 Corinthians 15:3-4 ... Christ died for our sins according to the Scriptures, ⁴ and that He was buried (proof of the death), and that He was raised on the third day according to the Scriptures,

God is holy and he cannot wink at sin or overlook it. Sin must be judged. Jesus lived a sinless life and he died in our place. God poured his wrath down on Jesus while he was on the cross. The sin debt was paid in full. While on the cross, Jesus said, "It is finished". 

All one has to do is 'believe on the Lord Jesus Christ' to be saved (Acts 16:31)
To believe means to trust in Christ alone to save you and it is his finished work on the cross that allows you access into heaven.

Ephesians 2:8,9 says, "For by grace (undeserved favor) you have been saved (delivered from sin's penalty) through faith, and that not of yourselves; it is a gift of God, not of works, that no one should boast."

God is the one that saves by his grace and not because of our 'good works'. Remember that your good works are like dirty rags to God (Isaiah 64:6). You could never do enough good works to be saved. It is God's grace alone that saves you.

What is keeping you from trusting Christ as your savior?

This is the most important decision that you will ever make.
You are not promised tomorrow. Many people die unexpectedly everyday.

After you die, where will you spend eternity?

    or  ?

There is no third option.

Eternal separation from God can be avoided (i.e hell), because of what Jesus did on the cross.

Admit to God that you are a sinner.
Believe (trust) that it is Jesus alone that can save you from your sins.
Confess with your mouth that Jesus is God.

1 John 5:13 These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life (after life with God in heaven).

Get involved in a church immediately.
Pray (talk to God continually)
Read your Bible daily
Just as a newborn baby needs food to grow. Christians need their spiritual food (Bible) to grow in their faith.

If you have more questions about having 100% assurance in going to heaven or if you have just accepted Christ as your Savior, please contact me.

Grace and Peace,
Brian