Soldier of Jesus Christ.

2 Timothy 2:3

King James Version

3 Thou therefore endure hardness, as a good soldier of Jesus Christ.

Hebrews 5:13-14

King James Version

13 For every one that useth milk is unskilful in the word of righteousness: for he is a babe.

14 But strong meat belongeth to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil.