Yes, I believe we will be alive after we die. But how we will be is what matters. We need to trust God to have us ready for it to be good. Or else, we will reap what is not good. So, it is not wise to come up with make-believe stuff about why we doubt, when we will reap so much more, later, than we have sowed now.
"Do not be deceived, God is not mocked; for whatever a man sows, that he will also reap. For he who sows to his flesh will of the flesh reap corruption, but he who sows to the Spirit will of the Spirit reap everlasting life." (Galatians 6:7-8)
We will reap so much more than our little seeds we sow during this life! There will be so much more, later, after we die.
And now how we are becoming in this life is our sample of how we will become much more after we die. Even now, we already are reaping emotionally according to what we have been sowing.
For example, there is arguing which is clearly anti-love. And as people keep arguing in their selfish way, they keep getting worse and worse, and their marriages get worse and worse. And complaining, instead of trusting God, can also help a person to keep reaping emotional trouble, even before they die.
So, we need to invest, then, in sowing what is good, instead >
"Do all things without complaining and disputing, that you may become blameless and harmless, children of God without fault in the midst of a crooked and perverse generation, among whom you shine as lights in the world, holding fast the word of life," (in Philippians 2:13-16)
We need how God has us stop our arguing and complaining, and trust God to change us to how He has us being in His love; then grow in this so we reap this for eternity.
"Love has been perfected among us in this: that we may have boldness in the day of judgment; because as He is, so are we in this world." (1 John 4:17)
Yes, not only will there be life, but there will be the day of judgment, after this life. We will be evaluated for if we have been perfected in God's love so we are pleasing to Him like Jesus.
So, we need to sow our seeds for this, so we reap this.