Perhaps you may consider it is you that have the problem. Context in scripture is key here. The New Testament was written in Koine (Common) Greek.
The Book of Matthew 5 - see verse 48
τέλειος (teleios)
Strong: G5046
GK: G5455
brought to completion; fully accomplished, fully developed,
Jas. 1:4a; fully realized, thorough,
1 Jn. 4:18; complete, entire, as opposed to what is partial and limited,
1 Cor. 13:10; full grown of ripe age,
1 Cor. 14:20;
Eph. 4:13;
Heb. 5:14; fully accomplished in Christian enlightenment,
1 Cor. 2:6;
Phil. 3:15;
Col. 1:28; perfect in some point of character,
without shortcoming in respect of a certain standard, Mt. 5:48;
19:21;
Col. 4:12;
Jas. 1:4b;
3:2; perfect, consummate,
Rom. 12:2;
Jas. 1:17,
25; compar. of higher excellence and efficiency,
Heb. 9:11