The flesh isn't bad. It will always sin, but it can be used for God. It's just that the flesh will fade away, but the spirit is the one that remains.
And Jesus baptism is where He took our sins. Both the Old Testament and the New Testament coincide with each other, Meaning, each verse has a back-up. In the Old Testament, the sins of Israel were paid for through the sacrifice of an animal. A priest from the Aaronic priesthood would lay his hands on the animal, and the sins of Israel were passed onto the animal. Then, the animal was killed, and the sins of Israel were paid for for an entire year. But, the blood of an animal was only temporal. So, God sent His son. Jesus is known as the Lamb of God. That's because Jesus was our sacrificial offering. John the Baptist, the one who baptized Jesus comes from the lineage of the Aaronic priesthood. So, in fact, he was qualified to pass the sins of the entire world onto Jesus. Unlike the animal, Jesus wasn't killed immediately. Instead, He lived His life for three years, for us. Then, He died, and resurrected three days later. The only reason Christ died, was because He had our sin on Him. Because a sinless man, cannot die. "For the wages of sin is death.."
Jesus was sinless. But, because our sins were on Him, and He became our sin bearer, He had to. There was no other choice.
This is basically a short version of it all. There's a reason the Bible is written the way it is.
God bless.