No. it is not necessary to have certification to enter SAP world.
Your certification will be a additional qualification for your experience..
Just concentrate about your knowledge.
Take a deep knowledge about SAP BASIS.
Suppose you have done certification but you haven't much knowledge about technical knowledge..
But one other person has strong technical knowledge but he doesn't has any certification.
Always the first priority will be the second guy.
And if you have the certification and strong technical knowledge then you will rock...
Decision is yours.
Best of luck for your career..
Regards