We can say for certain that everyone who rejects Jesus won't be in Heaven, because that is what Jesus told us:
John 3:18
Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.
We know that some who call themselves Christians won't make it, because He said this:
Matthew 7:21
Not everyone who says to Me, 'Lord, Lord,' will enter the kingdom of heaven, but only he who does the will of My Father in heaven.
The most important thing in this life is to make sure we are born again and that Jesus Christ truly is our Lord and Savior. God loves us, this is true; His love sent Jesus to the cross. You must also understand that it was Gods holiness that required it. God also requires us to repent and turn from our sins; faith without repentance is not a saving faith.