4:14 if. The sense here is not one of uncertainty, but of declaration. That is, “[since] we believe that Jesus died and rose again.” Note also that there is no other condition than just this condition for a believer to participate in the resurrection and rapture. All born-again Christians, having real faith in the substitutionary death and bodily resurrection of Christ, will be caught up to be with Christ when He comes, just as will all believers who died in faith.
4:14 in Jesus. “In Jesus” here actually is “through Jesus” (Greek preposition is dia). Believers are often said to be “in Christ,” but never “in Jesus.” Our “sleep” is made only that through the real death of the human Jesus, but our souls go to be “with Christ” (Philippians 1:23), the resurrected Lord in heaven. Because He died, we only sleep, awaiting His return. Thus the believer’s death is only physical, partially illustrated by the dream state, when the body lies still in bed while the soul and spirit are very conscious and active. These “will God bring with Him” when Christ returns (see also I Thessalonians 4:13).