Tim Tebow has always had doubters. They were there before he was even born.
Doctors in the Philippines, where his parents lived as Baptist missionaries, never expected him to be born alive.
His first high school coach in Florida forced him to play linebacker and tight end. He switched schools.
Analysts wondered aloud if he had the passing skills required to be a starting quarterback in college. He won a Heisman Trophy and two national championships at Florida.
NFL scouts had him pegged as a tight end or H-back at the pro level. He was drafted in the first round, became a starting quarterback and even won a playoff game.
Nathan Whitaker co-wrote Tebow's book, "Through My Eyes," published last May.
"He just really kind of thrives on [doubters],'' Whitaker said. "He would love for people to believe in him and he probably thrives on faith more than on the doubts, but the doubts, he does rally around that and it gives him a drive."
Now one of the most polarizing figures in all of sports is coming to its biggest stage. Tebow will become the newest member of the Jets, traded from the Broncos Wednesday, a day after Peyton Manning signed in Denver. Tebow is expected to be used as a situational quarterback on goal-line and gimmick plays, not as a possible replacement for Mark Sanchez. A backup with benefits.
That is, of course, unless he can prove his doubters wrong once again.
"He's so competitive that he certainly will work as if he can be the starter," Whitaker said. "He'll be one of those guys who will take it seriously when you tell him, 'You're just a play away from getting in the game.'
"When he was playing behind Chris Leak at Florida and playing behind Kyle [Orton] his first year in Denver, he certainly understood his role and prepared for that. That's a part of him. He sees the bigger picture."
Tebow was a heralded high school quarterback, and his prominence grew in college. But it wasn't until last season that he became a full-blown phenomenon.
Tebowmania swept the country as he led comeback wins in remarkable, sometimes inexplicable fashion. There was the 18-15 win over the Dolphins in overtime after erasing a late 15-0 deficit. There was his 95-yard drive against the Jets, capped by his 20-yard touchdown run. His 80-yard pass to Demaryius Thomas on the first play of overtime beat the Steelers in a wild-card playoff game.
Tebow was able to produce these victories while displaying few of the basic passing skills most NFL quarterbacks have mastered. That surprised, titillated and infuriated those who were following him closely.
It wasn't only his football heroics that drew attention. Tebow, a devout Christian, routinely thanked his "Lord and Savior, Jesus Christ" for all of his accomplishments. His genuflection in prayer during and after games became known as "Tebowing," and it became such a rage that celebrities and non-football players were imitating -- and often mocking -- it. There were even students at Riverhead High School who were suspended for "Tebowing" in the halls.
That's quite a rise for a baby who was not expected to live. Tebow's mother, Pam, was recovering from a coma after becoming ill from drinking contaminated water in the Philippines, and she was treated with strong drugs while pregnant. The drugs caused a condition called placental abruption, in which the placenta detaches from the uterine wall and the fetus is robbed of oxygen and nutrients. Doctors expected a stillbirth and urged her to abort the pregnancy.
Tebow was raised in Jacksonville, home-schooled by his mother with four older siblings. Unhappy with his local high school's football team, he moved to an apartment in a district with a more pass-oriented team. He twice was named Florida's Player of the Year.
As a freshman at Florida, he backed up Leak on the 2006 national champions. Tebow would come in for selected plays and situations. Although he didn't start the game, he threw for and ran for a touchdown in the BCS title game against Ohio State.
The next year he started and set SEC records for rushing touchdowns (20) and total TDs (55), and Tebow became the first sophomore ever to win the Heisman. The second championship would come in 2008.
Even with those accomplishments, his faith sometimes would overshadow his performance. Tebow became known for writing the chapter and verse of scripture on the eye black he wore on his face. The NCAA has since banned that practice, now known as "The Tebow Rule."
When his college career was over, the 6-3, 236-pounder ranked second all-time in career passing efficiency (170.8) and passing yards per attempt (9.33). He also held SEC records for rushing touchdowns (57), touchdowns (145) and rushing yards by a quarterback (2,947).
Tebow would bring all of that -- the accomplishments, the detractors, the believers, the defenders, the skeptics -- with him to the Jets.
"I think New York, the Jets, they might be a good fit for him," Whitaker said. "There's already so much noise in the system there. There's already drama and intrigue. What's a little more versus a club where everything is going well and all of a sudden you have Tebow followers and Tebow detractors who are causing chaos? There's already chaos."