Sergio Humberto Cuartas (“Cuartas”) and Jenny Stella Alvarez-Varela, and their children, Daniel Cuartas and Felipe Cuartas (collectively, “Petitioners”), all natives and citizens of Colombia, petition for review of the final order of the Board of Immigration Appeals (“BIA”), which affirmed without opinion the immigration judge’s (“IJ”) denial of asylum and withholding of removal under the Immigration and Nationality Act (“INA”) and the United Nations Convention Against Torture and Other Cruel, Inhuman, or Degrading Treatment or Punishment (“CAT”). On appeal, Petitioners argue that the IJ erred by denying their petition for asylum, under the INA, after finding that they did not demonstrate past persecution or a well-founded fear of future persecution, on a country-wide basis, by the Revolutionary Armed Forces of Colombia (“FARC”) based on Cuartas’s outspoken political activities that were in conflict with the FARC’s mission. 1 After careful review, we affirm.

When the BIA issues an affirmance without opinion, the IJ’s decision becomes *932 the final order subject to review. See Mendoza v. Att’y Gen., 327 F.3d 1283, 1284 n. 1 (11th Cir. 2003). As the fact-finder, it is the IJ’s duty to determine credibility, and we will not substitute our judgment for that of the IJ with respect to credibility findings. See Vasquez-Mondragon v. INS, 560 F.2d 1225, 1226 (5th Cir. 1977) (citation omitted). 2 The IJ’s factual determination that an alien is not entitled to asylum must be upheld if it is supported by substantial evidence. See Mazariegos v. Att’y Gen., 241 F.3d 1320, 1323 (11th Cir. 2001). Under this highly deferential standard of review, a denial of asylum may be reversed only if the evidence would compel a reasonable factfinder to find that the requisite fear of persecution exists. See INS v. Elias-Zacarias, 502 U.S. 478, 481 n. 1, 112 S.Ct. 812, 815 n. 1, 117 L.Ed.2d 38 (1992); see also 8 U.S.C. § 1252(b)(4)(B) (“administrative findings of fact are conclusive unless any reasonable adjudicator would be compelled to conclude to the contrary”).

An alien who arrives in or is present in the United States may apply for asylum. See INA § 208(a)(1), 8 U.S.C. § 1158(a)(1). The Attorney General has discretion to grant asylum if the alien meets the INA’s definition of a “refugee.” See INA § 208(b)(1), 8 U.S.C. § 1158(b)(1). A “refugee” is any person who is unwilling to return to his home country or to avail himself of that country’s protection “because of persecution or a well-founded fear of persecution on account of race, religion, nationality, membership in a particular social group, or political opinion.... ” 8 U.S.C. § 1101(a)(42)(A).

The asylum applicant carries the burden of proving statutory “refugee” status. See Najjar v. Ashcroft, 257 F.3d 1262, 1284 (11th Cir. 2001); 8 C.F.R. § 208.13(a). The applicant satisfies this burden by showing, with specific and credible evidence: (1) past persecution on account of a statutorily listed factor, or (2) a “well-founded fear” that his or her statutorily listed factor will cause future persecution. 8 C.F.R. § 208.13(a), (b); Najjar, 257 F.3d at 1287. “[Pjersecution is an extreme concept, requiring more than a few isolated incidents of verbal harassment or intimidation.” Sepulveda v. U.S. Att’y Gen., 378 F.3d 1260, 1264 (11th Cir. 2004) (citation and internal quotation marks omitted). Put another way, “[m]ere harassment does not amount to persecution.” Id. (citation omitted). An asylum applicant may not show merely that he has a political opinion, but must show that he was persecuted because of that opinion. Elias-Zacarias, 502 U.S. at 483,112 S.Ct. 812,117 L.Ed.2d 38.

If the alien establishes past persecution, it is presumed that his life or freedom would be threatened upon return to the country of removal unless the government shows by a preponderance that the country’s conditions have changed such that the applicant’s life or freedom would no longer be threatened or that the alien could relocate within the country and it would be reasonable to expect him to do so. See 8 *933 C.F.R. §§ 208.13(b), 208.16(b). An alien who has not shown past persecution may still be entitled to asylum if he can demonstrate a future threat to his life or freedom on a protected ground in his country. 8 C.F.R. §§ 208.13(b)(2), 208.16(b)(2). To establish a “well-founded fear,” “an applicant must demonstrate that his fear of persecution is subjectively genuine and objectively reasonable.” Najjar, 257 F.3d at 1289. “An imputed political opinion, whether correctly or incorrectly attributed, may constitute a ground for a ‘well-founded fear’ of political persecution within the meaning of the INA.” Id (citation omitted). However, as with past persecution, if the IJ properly finds that the alien could avoid a future threat by relocating to another part of his country, he cannot demonstrate a well-founded fear of persecution. 8 C.F.R. §§ 208.13(b)(l)-(2), 208.16(b)(l)(2).

Here, substantial evidence supports the IJ’s finding that Petitioners failed to demonstrate asylum eligibility because they did not establish past persecution or a well-founded fear of future persecution on account of a statutorily listed factor. Although Cuartas testified that his political opinion and related activities were contrary to the FARC and its mission, we can find no indication that the FARC was aware of Cuartas’s political opinion or ever persecuted him on account of that opinion. Cuartas testified that he was kidnaped by FARC members who asked him “where [he] was headed that day, what [he] had done that week, whether [he] had participated in any political events,” what he thought of the country, and whether he participated in any political groups. They also tried to recruit them to their cause to which he agreed in order to be released. After his release, FARC members made numerous harassing phone calls to his house.

The IJ found that Cuartas’s testimony did not sufficiently link the kidnaping or the phone calls to his political opinion for purposes of asylum. Cuartas’s testimony, then, without more, established only that he suffered harassment from the FARC, but not to a degree sufficient to constitute persecution and not on account of a statutorily protected ground. 3 Cf. Sanchez v. Att’y Gen., 392 F.3d 434, 438 (11th Cir. 2004) (finding that petitioner’s claim, based on harassment by FARC guerillas and petitioner’s failure to cooperate with the guerrillas or to join their forces, did not establish persecution for purposes of withholding of removal under INA). Threats or harassment, alone, do not constitute persecution on account of a statutorily protected ground. See Vatulev v. Ashcroft, 354 F.3d 1207, 1210 (10th Cir. 2003); Mikhailevitch v. INS, 146 F.3d 384, 390 (6th Cir. 1998).

Because Petitioners did not show that they suffered past persecution or a well-founded fear of future persecution based on a protected ground, or that they are unable to relocate within Colombia, they did not establish eligibility for asylum. See 8 C.F.R. § 208.13(a), (b); Najjar, 257 F.3d at 1287, 1293. Accordingly, we deny *934 their petition for review. 4

PETITION DENIED.