The baptism with fire is the sanctification of the believers. The fire means also the lake of fire for those who don't obey the gospel of Jesus Christ, John the Baptist said:
"He will baptize you with the Holy Spirit and fire. His winnowing fan is in His hand, and He will thoroughly clean out His threshing floor, and gather His wheat into the barn; but He will burn up the chaff with unquenchable fire." (Matthew 3:11, NKJV)
How can we enter God's kingdom?
We can enter it when we believe in Jesus et are born again and are part of an assembly of born again believers.
Jesus answered, Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. (John 3:5, NKJV).
