Is it as simple as just believe him and there is a place booked in paradise for followers?
Yes. But the key is to believe Jesus alone. Trust in him alone.
"Sirs, what must I do to be saved? 31 And they said, Believe on the Lord Jesus Christ, and you shall be saved, and your house." - Acts 16
" That if you shall confess with your mouth the Lord Jesus, and shall believe in your heart that God has raised him from the dead, you shall be saved. 10 For with the heart man believes to righteousness; and with the mouth confession is made to salvation. - Romans 10
The offer from God is nullified by trusting in him and another object of salvation..... like we did with the Watchtower, or like other groups do with their churches or church leaders.
If you will put on Christ like a parachute and trust in him like a parachute, you will be saved from judgment, and be ushered immediately into heaven with God at death. Later, you will get your body back, only better at the resurrection.
However, you cannont put on a parachute and then rely on flapping your arms to help the parachute. Or, you cannot trust in the parachute and at same time trust in the plane that is going down.
It doesn't work like that.
One act of disbelief sold us into sin and death, and because of the blood payment, one act of belief gets us freedom and life. One we had no control over, .... one we do. Because of Jesus, we have the same choice Adam and Eve faced in the beginning - whom to believe.
Many will testify that just asking God to give them this belief will get the relationship going. It did for me.