Is it permissible to marry a religious female colleague who is five years my senior, while I am already married and have children?

There is no objection to marrying a colleague or anyone else if the man is able to bear the financial burdens of marriage and to be just between two wives. However, if he fears injustice and does not feel confident in himself to be just, then it is not permissible for him to marry at that time, due to the Almighty's saying: "But if you fear that you will not be just, then [marry only] one."